2** 2001-09-15
4** The author disclaims copyright to this source code. In place of
5** a legal notice, here is a blessing:
7** May you do good and not evil.
8** May you find forgiveness for yourself and forgive others.
9** May you share freely, never taking more than you give.
12** This header file defines the interface that the SQLite library
13** presents to client programs. If a C-function, structure, datatype,
14** or constant definition does not appear in this file, then it is
15** not a published API of SQLite, is subject to change without
16** notice, and should not be referenced by programs that use SQLite.
18** Some of the definitions that are in this file are marked as
19** "experimental". Experimental interfaces are normally new
20** features recently added to SQLite. We do not anticipate changes
21** to experimental interfaces but reserve the right to make minor changes
22** if experience from use "in the wild" suggest such changes are prudent.
24** The official C-language API documentation for SQLite is derived
25** from comments in this file. This file is the authoritative source
26** on how SQLite interfaces are supposed to operate.
28** The name of this file under configuration management is "sqlite.h.in".
29** The makefile makes some minor changes to this file (such as inserting
30** the version number) and changes its name to "sqlite3.h" as
31** part of the build process.
33#ifndef SQLITE3_H
34#define SQLITE3_H
35#include <stdarg.h> /* Needed for the definition of va_list */
38** Make sure we can call this stuff from C++.
40#ifdef __cplusplus
41extern "C" {
46** Provide the ability to override linkage features of the interface.
49# define SQLITE_EXTERN extern
51#ifndef SQLITE_API
52# define SQLITE_API
54#ifndef SQLITE_CDECL
55# define SQLITE_CDECL
67# define SQLITE_SYSAPI
71** These no-op macros are used in front of interfaces to mark those
72** interfaces as either deprecated or experimental. New applications
73** should not use deprecated interfaces - they are supported for backwards
74** compatibility only. Application writers should be aware that
75** experimental interfaces are subject to change in point releases.
77** These macros used to resolve to various kinds of compiler magic that
78** would generate warning messages when they were used. But that
79** compiler magic ended up generating such a flurry of bug reports
80** that we have taken it all out and gone back to using simple
81** noop macros.
87** Ensure these symbols were not defined by some previous header file.
97** CAPI3REF: Compile-Time Library Version Numbers
99** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
100** evaluates to a string literal that is the SQLite version in the
101** format "X.Y.Z" where X is the major version number (always 3 for
102** SQLite3) and Y is the minor version number and Z is the release number.)^
103** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
104** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
105** numbers used in [SQLITE_VERSION].)^
106** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
107** be larger than the release from which it is derived. Either Y will
108** be held constant and Z will be incremented or else Y will be incremented
109** and Z will be reset to zero.
111** Since [version 3.6.18] ([dateof:3.6.18]),
112** SQLite source code has been stored in the
113** <a href="http://www.fossil-scm.org/">Fossil configuration management
114** system</a>. ^The SQLITE_SOURCE_ID macro evaluates to
115** a string which identifies a particular check-in of SQLite
116** within its configuration management system. ^The SQLITE_SOURCE_ID
117** string contains the date and time of the check-in (UTC) and a SHA1
118** or SHA3-256 hash of the entire source tree. If the source code has
119** been edited in any way since it was last checked in, then the last
120** four hexadecimal digits of the hash may be modified.
122** See also: [sqlite3_libversion()],
123** [sqlite3_libversion_number()], [sqlite3_sourceid()],
124** [sqlite_version()] and [sqlite_source_id()].
126#define SQLITE_VERSION "3.27.2"
127#define SQLITE_VERSION_NUMBER 3027002
128#define SQLITE_SOURCE_ID "2019-02-25 16:06:06 bd49a8271d650fa89e446b42e513b595a717b9212c91dd384aab871fc1d0f6d7"
131** CAPI3REF: Run-Time Library Version Numbers
132** KEYWORDS: sqlite3_version sqlite3_sourceid
134** These interfaces provide the same information as the [SQLITE_VERSION],
135** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
136** but are associated with the library instead of the header file. ^(Cautious
137** programmers might include assert() statements in their application to
138** verify that values returned by these interfaces match the macros in
139** the header, and thus ensure that the application is
140** compiled with matching library and header files.
142** <blockquote><pre>
143** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
144** assert( strncmp(sqlite3_sourceid(),SQLITE_SOURCE_ID,80)==0 );
145** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
146** </pre></blockquote>)^
148** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
149** macro. ^The sqlite3_libversion() function returns a pointer to the
150** to the sqlite3_version[] string constant. The sqlite3_libversion()
151** function is provided for use in DLLs since DLL users usually do not have
152** direct access to string constants within the DLL. ^The
153** sqlite3_libversion_number() function returns an integer equal to
154** [SQLITE_VERSION_NUMBER]. ^(The sqlite3_sourceid() function returns
155** a pointer to a string constant whose value is the same as the
156** [SQLITE_SOURCE_ID] C preprocessor macro. Except if SQLite is built
157** using an edited copy of [the amalgamation], then the last four characters
158** of the hash might be different from [SQLITE_SOURCE_ID].)^
160** See also: [sqlite_version()] and [sqlite_source_id()].
162SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
163SQLITE_API const char *sqlite3_libversion(void);
164SQLITE_API const char *sqlite3_sourceid(void);
165SQLITE_API int sqlite3_libversion_number(void);
168** CAPI3REF: Run-Time Library Compilation Options Diagnostics
170** ^The sqlite3_compileoption_used() function returns 0 or 1
171** indicating whether the specified option was defined at
172** compile time. ^The SQLITE_ prefix may be omitted from the
173** option name passed to sqlite3_compileoption_used().
175** ^The sqlite3_compileoption_get() function allows iterating
176** over the list of options that were defined at compile time by
177** returning the N-th compile time option string. ^If N is out of range,
178** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_
179** prefix is omitted from any strings returned by
180** sqlite3_compileoption_get().
182** ^Support for the diagnostic functions sqlite3_compileoption_used()
183** and sqlite3_compileoption_get() may be omitted by specifying the
184** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
186** See also: SQL functions [sqlite_compileoption_used()] and
187** [sqlite_compileoption_get()] and the [compile_options pragma].
190SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
191SQLITE_API const char *sqlite3_compileoption_get(int N);
195** CAPI3REF: Test To See If The Library Is Threadsafe
197** ^The sqlite3_threadsafe() function returns zero if and only if
198** SQLite was compiled with mutexing code omitted due to the
199** [SQLITE_THREADSAFE] compile-time option being set to 0.
201** SQLite can be compiled with or without mutexes. When
202** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
203** are enabled and SQLite is threadsafe. When the
204** [SQLITE_THREADSAFE] macro is 0,
205** the mutexes are omitted. Without the mutexes, it is not safe
206** to use SQLite concurrently from more than one thread.
208** Enabling mutexes incurs a measurable performance penalty.
209** So if speed is of utmost importance, it makes sense to disable
210** the mutexes. But for maximum safety, mutexes should be enabled.
211** ^The default behavior is for mutexes to be enabled.
213** This interface can be used by an application to make sure that the
214** version of SQLite that it is linking against was compiled with
215** the desired setting of the [SQLITE_THREADSAFE] macro.
217** This interface only reports on the compile-time mutex setting
218** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with
219** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
220** can be fully or partially disabled using a call to [sqlite3_config()]
222** or [SQLITE_CONFIG_SERIALIZED]. ^(The return value of the
223** sqlite3_threadsafe() function shows only the compile-time setting of
224** thread safety, not any run-time changes to that setting made by
225** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
226** is unchanged by calls to sqlite3_config().)^
228** See the [threading mode] documentation for additional information.
230SQLITE_API int sqlite3_threadsafe(void);
233** CAPI3REF: Database Connection Handle
234** KEYWORDS: {database connection} {database connections}
236** Each open SQLite database is represented by a pointer to an instance of
237** the opaque structure named "sqlite3". It is useful to think of an sqlite3
238** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and
239** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
240** and [sqlite3_close_v2()] are its destructors. There are many other
241** interfaces (such as
242** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
243** [sqlite3_busy_timeout()] to name but three) that are methods on an
244** sqlite3 object.
246typedef struct sqlite3 sqlite3;
249** CAPI3REF: 64-Bit Integer Types
250** KEYWORDS: sqlite_int64 sqlite_uint64
252** Because there is no cross-platform way to specify 64-bit integer types
253** SQLite includes typedefs for 64-bit signed and unsigned integers.
255** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
256** The sqlite_int64 and sqlite_uint64 types are supported for backwards
257** compatibility only.
259** ^The sqlite3_int64 and sqlite_int64 types can store integer values
260** between -9223372036854775808 and +9223372036854775807 inclusive. ^The
261** sqlite3_uint64 and sqlite_uint64 types can store integer values
262** between 0 and +18446744073709551615 inclusive.
264#ifdef SQLITE_INT64_TYPE
265 typedef SQLITE_INT64_TYPE sqlite_int64;
266# ifdef SQLITE_UINT64_TYPE
267 typedef SQLITE_UINT64_TYPE sqlite_uint64;
268# else
269 typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
270# endif
271#elif defined(_MSC_VER) || defined(__BORLANDC__)
272 typedef __int64 sqlite_int64;
273 typedef unsigned __int64 sqlite_uint64;
275 typedef long long int sqlite_int64;
276 typedef unsigned long long int sqlite_uint64;
278typedef sqlite_int64 sqlite3_int64;
279typedef sqlite_uint64 sqlite3_uint64;
282** If compiling for a processor that lacks floating point support,
283** substitute integer for floating-point.
286# define double sqlite3_int64
290** CAPI3REF: Closing A Database Connection
291** DESTRUCTOR: sqlite3
293** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
294** for the [sqlite3] object.
295** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
296** the [sqlite3] object is successfully destroyed and all associated
297** resources are deallocated.
299** ^If the database connection is associated with unfinalized prepared
300** statements or unfinished sqlite3_backup objects then sqlite3_close()
301** will leave the database connection open and return [SQLITE_BUSY].
302** ^If sqlite3_close_v2() is called with unfinalized prepared statements
303** and/or unfinished sqlite3_backups, then the database connection becomes
304** an unusable "zombie" which will automatically be deallocated when the
305** last prepared statement is finalized or the last sqlite3_backup is
306** finished. The sqlite3_close_v2() interface is intended for use with
307** host languages that are garbage collected, and where the order in which
308** destructors are called is arbitrary.
310** Applications should [sqlite3_finalize | finalize] all [prepared statements],
311** [sqlite3_blob_close | close] all [BLOB handles], and
312** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
313** with the [sqlite3] object prior to attempting to close the object. ^If
314** sqlite3_close_v2() is called on a [database connection] that still has
315** outstanding [prepared statements], [BLOB handles], and/or
316** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
317** of resources is deferred until all [prepared statements], [BLOB handles],
318** and [sqlite3_backup] objects are also destroyed.
320** ^If an [sqlite3] object is destroyed while a transaction is open,
321** the transaction is automatically rolled back.
323** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
324** must be either a NULL
325** pointer or an [sqlite3] object pointer obtained
326** from [sqlite3_open()], [sqlite3_open16()], or
327** [sqlite3_open_v2()], and not previously closed.
328** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
329** argument is a harmless no-op.
331SQLITE_API int sqlite3_close(sqlite3*);
332SQLITE_API int sqlite3_close_v2(sqlite3*);
335** The type for a callback function.
336** This is legacy and deprecated. It is included for historical
337** compatibility and is not documented.
339typedef int (*sqlite3_callback)(void*,int,char**, char**);
342** CAPI3REF: One-Step Query Execution Interface
343** METHOD: sqlite3
345** The sqlite3_exec() interface is a convenience wrapper around
346** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
347** that allows an application to run multiple statements of SQL
348** without having to use a lot of C code.
350** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
351** semicolon-separate SQL statements passed into its 2nd argument,
352** in the context of the [database connection] passed in as its 1st
353** argument. ^If the callback function of the 3rd argument to
354** sqlite3_exec() is not NULL, then it is invoked for each result row
355** coming out of the evaluated SQL statements. ^The 4th argument to
356** sqlite3_exec() is relayed through to the 1st argument of each
357** callback invocation. ^If the callback pointer to sqlite3_exec()
358** is NULL, then no callback is ever invoked and result rows are
359** ignored.
361** ^If an error occurs while evaluating the SQL statements passed into
362** sqlite3_exec(), then execution of the current statement stops and
363** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec()
364** is not NULL then any error message is written into memory obtained
365** from [sqlite3_malloc()] and passed back through the 5th parameter.
366** To avoid memory leaks, the application should invoke [sqlite3_free()]
367** on error message strings returned through the 5th parameter of
368** sqlite3_exec() after the error message string is no longer needed.
369** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
370** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
371** NULL before returning.
373** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
374** routine returns SQLITE_ABORT without invoking the callback again and
375** without running any subsequent SQL statements.
377** ^The 2nd argument to the sqlite3_exec() callback function is the
378** number of columns in the result. ^The 3rd argument to the sqlite3_exec()
379** callback is an array of pointers to strings obtained as if from
380** [sqlite3_column_text()], one for each column. ^If an element of a
381** result row is NULL then the corresponding string pointer for the
382** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the
383** sqlite3_exec() callback is an array of pointers to strings where each
384** entry represents the name of corresponding result column as obtained
385** from [sqlite3_column_name()].
387** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
388** to an empty string, or a pointer that contains only whitespace and/or
389** SQL comments, then no SQL statements are evaluated and the database
390** is not changed.
392** Restrictions:
394** <ul>
395** <li> The application must ensure that the 1st parameter to sqlite3_exec()
396** is a valid and open [database connection].
397** <li> The application must not close the [database connection] specified by
398** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
399** <li> The application must not modify the SQL statement text passed into
400** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
401** </ul>
403SQLITE_API int sqlite3_exec(
404 sqlite3*, /* An open database */
405 const char *sql, /* SQL to be evaluated */
406 int (*callback)(void*,int,char**,char**), /* Callback function */
407 void *, /* 1st argument to callback */
408 char **errmsg /* Error msg written here */
412** CAPI3REF: Result Codes
413** KEYWORDS: {result code definitions}
415** Many SQLite functions return an integer result code from the set shown
416** here in order to indicate success or failure.
418** New error codes may be added in future versions of SQLite.
420** See also: [extended result code definitions]
422#define SQLITE_OK 0 /* Successful result */
423/* beginning-of-error-codes */
424#define SQLITE_ERROR 1 /* Generic error */
425#define SQLITE_INTERNAL 2 /* Internal logic error in SQLite */
426#define SQLITE_PERM 3 /* Access permission denied */
427#define SQLITE_ABORT 4 /* Callback routine requested an abort */
428#define SQLITE_BUSY 5 /* The database file is locked */
429#define SQLITE_LOCKED 6 /* A table in the database is locked */
430#define SQLITE_NOMEM 7 /* A malloc() failed */
431#define SQLITE_READONLY 8 /* Attempt to write a readonly database */
432#define SQLITE_INTERRUPT 9 /* Operation terminated by sqlite3_interrupt()*/
433#define SQLITE_IOERR 10 /* Some kind of disk I/O error occurred */
434#define SQLITE_CORRUPT 11 /* The database disk image is malformed */
435#define SQLITE_NOTFOUND 12 /* Unknown opcode in sqlite3_file_control() */
436#define SQLITE_FULL 13 /* Insertion failed because database is full */
437#define SQLITE_CANTOPEN 14 /* Unable to open the database file */
438#define SQLITE_PROTOCOL 15 /* Database lock protocol error */
439#define SQLITE_EMPTY 16 /* Internal use only */
440#define SQLITE_SCHEMA 17 /* The database schema changed */
441#define SQLITE_TOOBIG 18 /* String or BLOB exceeds size limit */
442#define SQLITE_CONSTRAINT 19 /* Abort due to constraint violation */
443#define SQLITE_MISMATCH 20 /* Data type mismatch */
444#define SQLITE_MISUSE 21 /* Library used incorrectly */
445#define SQLITE_NOLFS 22 /* Uses OS features not supported on host */
446#define SQLITE_AUTH 23 /* Authorization denied */
447#define SQLITE_FORMAT 24 /* Not used */
448#define SQLITE_RANGE 25 /* 2nd parameter to sqlite3_bind out of range */
449#define SQLITE_NOTADB 26 /* File opened that is not a database file */
450#define SQLITE_NOTICE 27 /* Notifications from sqlite3_log() */
451#define SQLITE_WARNING 28 /* Warnings from sqlite3_log() */
452#define SQLITE_ROW 100 /* sqlite3_step() has another row ready */
453#define SQLITE_DONE 101 /* sqlite3_step() has finished executing */
454/* end-of-error-codes */
457** CAPI3REF: Extended Result Codes
458** KEYWORDS: {extended result code definitions}
460** In its default configuration, SQLite API routines return one of 30 integer
461** [result codes]. However, experience has shown that many of
462** these result codes are too coarse-grained. They do not provide as
463** much information about problems as programmers might like. In an effort to
464** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
465** and later) include
466** support for additional result codes that provide more detailed information
467** about errors. These [extended result codes] are enabled or disabled
468** on a per database connection basis using the
469** [sqlite3_extended_result_codes()] API. Or, the extended code for
470** the most recent error can be obtained using
471** [sqlite3_extended_errcode()].
476#define SQLITE_IOERR_READ (SQLITE_IOERR | (1<<8))
487#define SQLITE_IOERR_NOMEM (SQLITE_IOERR | (12<<8))
490#define SQLITE_IOERR_LOCK (SQLITE_IOERR | (15<<8))
491#define SQLITE_IOERR_CLOSE (SQLITE_IOERR | (16<<8))
497#define SQLITE_IOERR_SEEK (SQLITE_IOERR | (22<<8))
499#define SQLITE_IOERR_MMAP (SQLITE_IOERR | (24<<8))
502#define SQLITE_IOERR_VNODE (SQLITE_IOERR | (27<<8))
503#define SQLITE_IOERR_AUTH (SQLITE_IOERR | (28<<8))
515#define SQLITE_CANTOPEN_DIRTYWAL (SQLITE_CANTOPEN | (5<<8)) /* Not Used */
538#define SQLITE_AUTH_USER (SQLITE_AUTH | (1<<8))
542** CAPI3REF: Flags For File Open Operations
544** These bit values are intended for use in the
545** 3rd parameter to the [sqlite3_open_v2()] interface and
546** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
548#define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */
549#define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */
550#define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */
551#define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */
552#define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */
553#define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */
554#define SQLITE_OPEN_URI 0x00000040 /* Ok for sqlite3_open_v2() */
555#define SQLITE_OPEN_MEMORY 0x00000080 /* Ok for sqlite3_open_v2() */
556#define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */
557#define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */
558#define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */
559#define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */
560#define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */
561#define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */
562#define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */
563#define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */
564#define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */
565#define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */
566#define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */
567#define SQLITE_OPEN_WAL 0x00080000 /* VFS only */
569/* Reserved: 0x00F00000 */
572** CAPI3REF: Device Characteristics
574** The xDeviceCharacteristics method of the [sqlite3_io_methods]
575** object returns an integer which is a vector of these
576** bit values expressing I/O characteristics of the mass storage
577** device that holds the file that the [sqlite3_io_methods]
578** refers to.
580** The SQLITE_IOCAP_ATOMIC property means that all writes of
581** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
582** mean that writes of blocks that are nnn bytes in size and
583** are aligned to an address which is an integer multiple of
584** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
585** that when data is appended to a file, the data is appended
586** first then the size of the file is extended, never the other
587** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
588** information is written to disk in the same order as calls
589** to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
590** after reboot following a crash or power loss, the only bytes in a
591** file that were written at the application level might have changed
592** and that adjacent bytes, even bytes within the same sector are
593** guaranteed to be unchanged. The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
594** flag indicates that a file cannot be deleted when open. The
595** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
596** read-only media and cannot be changed even by processes with
597** elevated privileges.
599** The SQLITE_IOCAP_BATCH_ATOMIC property means that the underlying
600** filesystem supports doing multiple write operations atomically when those
601** write operations are bracketed by [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] and
604#define SQLITE_IOCAP_ATOMIC 0x00000001
605#define SQLITE_IOCAP_ATOMIC512 0x00000002
606#define SQLITE_IOCAP_ATOMIC1K 0x00000004
607#define SQLITE_IOCAP_ATOMIC2K 0x00000008
608#define SQLITE_IOCAP_ATOMIC4K 0x00000010
609#define SQLITE_IOCAP_ATOMIC8K 0x00000020
610#define SQLITE_IOCAP_ATOMIC16K 0x00000040
611#define SQLITE_IOCAP_ATOMIC32K 0x00000080
612#define SQLITE_IOCAP_ATOMIC64K 0x00000100
613#define SQLITE_IOCAP_SAFE_APPEND 0x00000200
614#define SQLITE_IOCAP_SEQUENTIAL 0x00000400
617#define SQLITE_IOCAP_IMMUTABLE 0x00002000
618#define SQLITE_IOCAP_BATCH_ATOMIC 0x00004000
621** CAPI3REF: File Locking Levels
623** SQLite uses one of these integer values as the second
624** argument to calls it makes to the xLock() and xUnlock() methods
625** of an [sqlite3_io_methods] object.
627#define SQLITE_LOCK_NONE 0
634** CAPI3REF: Synchronization Type Flags
636** When SQLite invokes the xSync() method of an
637** [sqlite3_io_methods] object it uses a combination of
638** these integer values as the second argument.
640** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
641** sync operation only needs to flush data to mass storage. Inode
642** information need not be flushed. If the lower four bits of the flag
643** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
644** If the lower four bits equal SQLITE_SYNC_FULL, that means
645** to use Mac OS X style fullsync instead of fsync().
647** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
648** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
649** settings. The [synchronous pragma] determines when calls to the
650** xSync VFS method occur and applies uniformly across all platforms.
651** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
652** energetic or rigorous or forceful the sync operations are and
653** only make a difference on Mac OSX for the default SQLite code.
654** (Third-party VFS implementations might also make the distinction
655** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
656** operating systems natively supported by SQLite, only Mac OSX
657** cares about the difference.)
659#define SQLITE_SYNC_NORMAL 0x00002
660#define SQLITE_SYNC_FULL 0x00003
661#define SQLITE_SYNC_DATAONLY 0x00010
664** CAPI3REF: OS Interface Open File Handle
666** An [sqlite3_file] object represents an open file in the
667** [sqlite3_vfs | OS interface layer]. Individual OS interface
668** implementations will
669** want to subclass this object by appending additional fields
670** for their own use. The pMethods entry is a pointer to an
671** [sqlite3_io_methods] object that defines methods for performing
672** I/O operations on the open file.
674typedef struct sqlite3_file sqlite3_file;
675struct sqlite3_file {
676 const struct sqlite3_io_methods *pMethods; /* Methods for an open file */
680** CAPI3REF: OS Interface File Virtual Methods Object
682** Every file opened by the [sqlite3_vfs.xOpen] method populates an
683** [sqlite3_file] object (or, more commonly, a subclass of the
684** [sqlite3_file] object) with a pointer to an instance of this object.
685** This object defines the methods used to perform various operations
686** against the open file represented by the [sqlite3_file] object.
688** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element
689** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
690** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The
691** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
692** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
693** to NULL.
695** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
696** [SQLITE_SYNC_FULL]. The first choice is the normal fsync().
697** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY]
698** flag may be ORed in to indicate that only the data of the file
699** and not its inode needs to be synced.
701** The integer values to xLock() and xUnlock() are one of
702** <ul>
703** <li> [SQLITE_LOCK_NONE],
704** <li> [SQLITE_LOCK_SHARED],
706** <li> [SQLITE_LOCK_PENDING], or
708** </ul>
709** xLock() increases the lock. xUnlock() decreases the lock.
710** The xCheckReservedLock() method checks whether any database connection,
711** either in this process or in some other process, is holding a RESERVED,
712** PENDING, or EXCLUSIVE lock on the file. It returns true
713** if such a lock exists and false otherwise.
715** The xFileControl() method is a generic interface that allows custom
716** VFS implementations to directly control an open file using the
717** [sqlite3_file_control()] interface. The second "op" argument is an
718** integer opcode. The third argument is a generic pointer intended to
719** point to a structure that may contain arguments or space in which to
720** write return values. Potential uses for xFileControl() might be
721** functions to enable blocking locks with timeouts, to change the
722** locking strategy (for example to use dot-file locks), to inquire
723** about the status of a lock, or to break stale locks. The SQLite
724** core reserves all opcodes less than 100 for its own use.
725** A [file control opcodes | list of opcodes] less than 100 is available.
726** Applications that define a custom xFileControl method should use opcodes
727** greater than 100 to avoid conflicts. VFS implementations should
728** return [SQLITE_NOTFOUND] for file control opcodes that they do not
729** recognize.
731** The xSectorSize() method returns the sector size of the
732** device that underlies the file. The sector size is the
733** minimum write that can be performed without disturbing
734** other bytes in the file. The xDeviceCharacteristics()
735** method returns a bit vector describing behaviors of the
736** underlying device:
738** <ul>
740** <li> [SQLITE_IOCAP_ATOMIC512]
754** </ul>
756** The SQLITE_IOCAP_ATOMIC property means that all writes of
757** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
758** mean that writes of blocks that are nnn bytes in size and
759** are aligned to an address which is an integer multiple of
760** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
761** that when data is appended to a file, the data is appended
762** first then the size of the file is extended, never the other
763** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
764** information is written to disk in the same order as calls
765** to xWrite().
767** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
768** in the unread portions of the buffer with zeros. A VFS that
769** fails to zero-fill short reads might seem to work. However,
770** failure to zero-fill short reads will eventually lead to
771** database corruption.
773typedef struct sqlite3_io_methods sqlite3_io_methods;
774struct sqlite3_io_methods {
775 int iVersion;
776 int (*xClose)(sqlite3_file*);
777 int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
778 int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
779 int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
780 int (*xSync)(sqlite3_file*, int flags);
781 int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
782 int (*xLock)(sqlite3_file*, int);
783 int (*xUnlock)(sqlite3_file*, int);
784 int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
785 int (*xFileControl)(sqlite3_file*, int op, void *pArg);
786 int (*xSectorSize)(sqlite3_file*);
787 int (*xDeviceCharacteristics)(sqlite3_file*);
788 /* Methods above are valid for version 1 */
789 int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
790 int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
791 void (*xShmBarrier)(sqlite3_file*);
792 int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
793 /* Methods above are valid for version 2 */
794 int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
795 int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
796 /* Methods above are valid for version 3 */
797 /* Additional methods may be added in future releases */
801** CAPI3REF: Standard File Control Opcodes
802** KEYWORDS: {file control opcodes} {file control opcode}
804** These integer constants are opcodes for the xFileControl method
805** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
806** interface.
808** <ul>
810** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This
811** opcode causes the xFileControl method to write the current state of
812** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
814** into an integer that the pArg argument points to. This capability
815** is used during testing and is only available when the SQLITE_TEST
816** compile-time option is used.
819** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
820** layer a hint of how large the database file will grow to be during the
821** current transaction. This hint is not guaranteed to be accurate but it
822** is often close. The underlying VFS might choose to preallocate database
823** file space based on this hint in order to help writes to the database
824** file run faster.
827** The [SQLITE_FCNTL_SIZE_LIMIT] opcode is used by in-memory VFS that
828** implements [sqlite3_deserialize()] to set an upper bound on the size
829** of the in-memory database. The argument is a pointer to a [sqlite3_int64].
830** If the integer pointed to is negative, then it is filled in with the
831** current limit. Otherwise the limit is set to the larger of the value
832** of the integer pointed to and the current database size. The integer
833** pointed to is set to the new limit.
836** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
837** extends and truncates the database file in chunks of a size specified
838** by the user. The fourth argument to [sqlite3_file_control()] should
839** point to an integer (type int) containing the new chunk-size to use
840** for the nominated database. Allocating database file space in large
841** chunks (say 1MB at a time), may reduce file-system fragmentation and
842** improve performance on some systems.
845** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
846** to the [sqlite3_file] object associated with a particular database
847** connection. See also [SQLITE_FCNTL_JOURNAL_POINTER].
850** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
851** to the [sqlite3_file] object associated with the journal file (either
852** the [rollback journal] or the [write-ahead log]) for a particular database
853** connection. See also [SQLITE_FCNTL_FILE_POINTER].
856** No longer in use.
858** <li>[[SQLITE_FCNTL_SYNC]]
859** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
860** sent to the VFS immediately before the xSync method is invoked on a
861** database file descriptor. Or, if the xSync method is not invoked
862** because the user has configured SQLite with
863** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place
864** of the xSync method. In most cases, the pointer argument passed with
865** this file-control is NULL. However, if the database file is being synced
866** as part of a multi-database commit, the argument points to a nul-terminated
867** string containing the transactions master-journal file name. VFSes that
868** do not need this signal should silently ignore this opcode. Applications
869** should not call [sqlite3_file_control()] with this opcode as doing so may
870** disrupt the operation of the specialized VFSes that do require it.
873** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
874** and sent to the VFS after a transaction has been committed immediately
875** but before the database is unlocked. VFSes that do not need this signal
876** should silently ignore this opcode. Applications should not call
877** [sqlite3_file_control()] with this opcode as doing so may disrupt the
878** operation of the specialized VFSes that do require it.
881** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
882** retry counts and intervals for certain disk I/O operations for the
883** windows [VFS] in order to provide robustness in the presence of
884** anti-virus programs. By default, the windows VFS will retry file read,
885** file write, and file delete operations up to 10 times, with a delay
886** of 25 milliseconds before the first retry and with the delay increasing
887** by an additional 25 milliseconds with each subsequent retry. This
888** opcode allows these two values (10 retries and 25 milliseconds of delay)
889** to be adjusted. The values are changed for all database connections
890** within the same process. The argument is a pointer to an array of two
891** integers where the first integer is the new retry count and the second
892** integer is the delay. If either integer is negative, then the setting
893** is not changed but instead the prior value of that setting is written
894** into the array entry, allowing the current retry settings to be
895** interrogated. The zDbName parameter is ignored.
898** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
899** persistent [WAL | Write Ahead Log] setting. By default, the auxiliary
900** write ahead log ([WAL file]) and shared memory
901** files used for transaction control
902** are automatically deleted when the latest connection to the database
903** closes. Setting persistent WAL mode causes those files to persist after
904** close. Persisting the files is useful when other processes that do not
905** have write permission on the directory containing the database file want
906** to read the database file, as the WAL and shared memory files must exist
907** in order for the database to be readable. The fourth parameter to
908** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
909** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
910** WAL mode. If the integer is -1, then it is overwritten with the current
911** WAL persistence setting.
914** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
915** persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting
916** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
917** xDeviceCharacteristics methods. The fourth parameter to
918** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
919** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
920** mode. If the integer is -1, then it is overwritten with the current
921** zero-damage mode setting.
924** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
925** a write transaction to indicate that, unless it is rolled back for some
926** reason, the entire database file will be overwritten by the current
927** transaction. This is used by VACUUM operations.
930** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
931** all [VFSes] in the VFS stack. The names are of all VFS shims and the
932** final bottom-level VFS are written into memory obtained from
933** [sqlite3_malloc()] and the result is stored in the char* variable
934** that the fourth parameter of [sqlite3_file_control()] points to.
935** The caller is responsible for freeing the memory when done. As with
936** all file-control actions, there is no guarantee that this will actually
937** do anything. Callers should initialize the char* variable to a NULL
938** pointer in case this file-control is not implemented. This file-control
939** is intended for diagnostic use only.
942** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
943** [VFSes] currently in use. ^(The argument X in
944** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
945** of type "[sqlite3_vfs] **". This opcodes will set *X
946** to a pointer to the top-level VFS.)^
947** ^When there are multiple VFS shims in the stack, this opcode finds the
948** upper-most shim only.
951** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA]
952** file control is sent to the open [sqlite3_file] object corresponding
953** to the database file to which the pragma statement refers. ^The argument
954** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
955** pointers to strings (char**) in which the second element of the array
956** is the name of the pragma and the third element is the argument to the
957** pragma or NULL if the pragma has no argument. ^The handler for an
958** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
959** of the char** argument point to a string obtained from [sqlite3_mprintf()]
960** or the equivalent and that string will become the result of the pragma or
961** the error message if the pragma fails. ^If the
962** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal
963** [PRAGMA] processing continues. ^If the [SQLITE_FCNTL_PRAGMA]
964** file control returns [SQLITE_OK], then the parser assumes that the
965** VFS has handled the PRAGMA itself and the parser generates a no-op
966** prepared statement if result string is NULL, or that returns a copy
967** of the result string if the string is non-NULL.
968** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
969** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
970** that the VFS encountered an error while handling the [PRAGMA] and the
971** compilation of the PRAGMA fails with an error. ^The [SQLITE_FCNTL_PRAGMA]
972** file control occurs at the beginning of pragma statement analysis and so
973** it is able to override built-in [PRAGMA] statements.
977** file-control may be invoked by SQLite on the database file handle
978** shortly after it is opened in order to provide a custom VFS with access
979** to the connections busy-handler callback. The argument is of type (void **)
980** - an array of two (void *) values. The first (void *) actually points
981** to a function of type (int (*)(void *)). In order to invoke the connections
982** busy-handler, this function should be invoked with the second (void *) in
983** the array as the only argument. If it returns non-zero, then the operation
984** should be retried. If it returns zero, the custom VFS should abandon the
985** current operation.
988** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
989** to have SQLite generate a
990** temporary filename using the same algorithm that is followed to generate
991** temporary filenames for TEMP tables and other internal uses. The
992** argument should be a char** which will be filled with the filename
993** written into memory obtained from [sqlite3_malloc()]. The caller should
994** invoke [sqlite3_free()] on the result to avoid a memory leak.
997** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
998** maximum number of bytes that will be used for memory-mapped I/O.
999** The argument is a pointer to a value of type sqlite3_int64 that
1000** is an advisory maximum number of bytes in the file to memory map. The
1001** pointer is overwritten with the old value. The limit is not changed if
1002** the value originally pointed to is negative, and so the current limit
1003** can be queried by passing in a pointer to a negative number. This
1004** file-control is used internally to implement [PRAGMA mmap_size].
1006** <li>[[SQLITE_FCNTL_TRACE]]
1007** The [SQLITE_FCNTL_TRACE] file control provides advisory information
1008** to the VFS about what the higher layers of the SQLite stack are doing.
1009** This file control is used by some VFS activity tracing [shims].
1010** The argument is a zero-terminated string. Higher layers in the
1011** SQLite stack may generate instances of this file control if
1012** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
1015** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
1016** pointer to an integer and it writes a boolean into that integer depending
1017** on whether or not the file has been renamed, moved, or deleted since it
1018** was first opened.
1021** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
1022** underlying native file handle associated with a file handle. This file
1023** control interprets its argument as a pointer to a native file handle and
1024** writes the resulting value there.
1027** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging. This
1028** opcode causes the xFileControl method to swap the file handle with the one
1029** pointed to by the pArg argument. This capability is used during testing
1030** and only needs to be supported when SQLITE_TEST is defined.
1033** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
1034** be advantageous to block on the next WAL lock if the lock is not immediately
1035** available. The WAL subsystem issues this signal during rare
1036** circumstances in order to fix a problem with priority inversion.
1037** Applications should <em>not</em> use this file-control.
1039** <li>[[SQLITE_FCNTL_ZIPVFS]]
1040** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
1041** VFS should return SQLITE_NOTFOUND for this opcode.
1043** <li>[[SQLITE_FCNTL_RBU]]
1044** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
1045** the RBU extension only. All other VFS should return SQLITE_NOTFOUND for
1046** this opcode.
1049** If the [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] opcode returns SQLITE_OK, then
1050** the file descriptor is placed in "batch write mode", which
1051** means all subsequent write operations will be deferred and done
1052** atomically at the next [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE]. Systems
1053** that do not support batch atomic writes will return SQLITE_NOTFOUND.
1054** ^Following a successful SQLITE_FCNTL_BEGIN_ATOMIC_WRITE and prior to
1055** the closing [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] or
1057** no VFS interface calls on the same [sqlite3_file] file descriptor
1058** except for calls to the xWrite method and the xFileControl method
1062** The [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] opcode causes all write
1063** operations since the previous successful call to
1064** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be performed atomically.
1065** This file control returns [SQLITE_OK] if and only if the writes were
1066** all performed successfully and have been committed to persistent storage.
1067** ^Regardless of whether or not it is successful, this file control takes
1068** the file descriptor out of batch write mode so that all subsequent
1069** write operations are independent.
1070** ^SQLite will never invoke SQLITE_FCNTL_COMMIT_ATOMIC_WRITE without
1071** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
1074** The [SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE] opcode causes all write
1075** operations since the previous successful call to
1076** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be rolled back.
1077** ^This file control takes the file descriptor out of batch write mode
1078** so that all subsequent write operations are independent.
1079** ^SQLite will never invoke SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE without
1080** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
1083** The [SQLITE_FCNTL_LOCK_TIMEOUT] opcode causes attempts to obtain
1084** a file lock using the xLock or xShmLock methods of the VFS to wait
1085** for up to M milliseconds before failing, where M is the single
1086** unsigned integer parameter.
1089** The [SQLITE_FCNTL_DATA_VERSION] opcode is used to detect changes to
1090** a database file. The argument is a pointer to a 32-bit unsigned integer.
1091** The "data version" for the pager is written into the pointer. The
1092** "data version" changes whenever any change occurs to the corresponding
1093** database file, either through SQL statements on the same database
1094** connection or through transactions committed by separate database
1095** connections possibly in other processes. The [sqlite3_total_changes()]
1096** interface can be used to find if any database on the connection has changed,
1097** but that interface responds to changes on TEMP as well as MAIN and does
1098** not provide a mechanism to detect changes to MAIN only. Also, the
1099** [sqlite3_total_changes()] interface responds to internal changes only and
1100** omits changes made by other database connections. The
1101** [PRAGMA data_version] command provide a mechanism to detect changes to
1102** a single attached database that occur due to other database connections,
1103** but omits changes implemented by the database connection on which it is
1104** called. This file control is the only mechanism to detect changes that
1105** happen either internally or externally and that are associated with
1106** a particular attached database.
1107** </ul>
1122#define SQLITE_FCNTL_PRAGMA 14
1126#define SQLITE_FCNTL_TRACE 19
1128#define SQLITE_FCNTL_SYNC 21
1132#define SQLITE_FCNTL_ZIPVFS 25
1133#define SQLITE_FCNTL_RBU 26
1137#define SQLITE_FCNTL_PDB 30
1145/* deprecated names */
1152** CAPI3REF: Mutex Handle
1154** The mutex module within SQLite defines [sqlite3_mutex] to be an
1155** abstract type for a mutex object. The SQLite core never looks
1156** at the internal representation of an [sqlite3_mutex]. It only
1157** deals with pointers to the [sqlite3_mutex] object.
1159** Mutexes are created using [sqlite3_mutex_alloc()].
1161typedef struct sqlite3_mutex sqlite3_mutex;
1164** CAPI3REF: Loadable Extension Thunk
1166** A pointer to the opaque sqlite3_api_routines structure is passed as
1167** the third parameter to entry points of [loadable extensions]. This
1168** structure must be typedefed in order to work around compiler warnings
1169** on some platforms.
1171typedef struct sqlite3_api_routines sqlite3_api_routines;
1174** CAPI3REF: OS Interface Object
1176** An instance of the sqlite3_vfs object defines the interface between
1177** the SQLite core and the underlying operating system. The "vfs"
1178** in the name of the object stands for "virtual file system". See
1179** the [VFS | VFS documentation] for further information.
1181** The VFS interface is sometimes extended by adding new methods onto
1182** the end. Each time such an extension occurs, the iVersion field
1183** is incremented. The iVersion value started out as 1 in
1184** SQLite [version 3.5.0] on [dateof:3.5.0], then increased to 2
1185** with SQLite [version 3.7.0] on [dateof:3.7.0], and then increased
1186** to 3 with SQLite [version 3.7.6] on [dateof:3.7.6]. Additional fields
1187** may be appended to the sqlite3_vfs object and the iVersion value
1188** may increase again in future versions of SQLite.
1189** Note that the structure
1190** of the sqlite3_vfs object changes in the transition from
1191** SQLite [version 3.5.9] to [version 3.6.0] on [dateof:3.6.0]
1192** and yet the iVersion field was not modified.
1194** The szOsFile field is the size of the subclassed [sqlite3_file]
1195** structure used by this VFS. mxPathname is the maximum length of
1196** a pathname in this VFS.
1198** Registered sqlite3_vfs objects are kept on a linked list formed by
1199** the pNext pointer. The [sqlite3_vfs_register()]
1200** and [sqlite3_vfs_unregister()] interfaces manage this list
1201** in a thread-safe way. The [sqlite3_vfs_find()] interface
1202** searches the list. Neither the application code nor the VFS
1203** implementation should use the pNext pointer.
1205** The pNext field is the only field in the sqlite3_vfs
1206** structure that SQLite will ever modify. SQLite will only access
1207** or modify this field while holding a particular static mutex.
1208** The application should never modify anything within the sqlite3_vfs
1209** object once the object has been registered.
1211** The zName field holds the name of the VFS module. The name must
1212** be unique across all VFS modules.
1214** [[sqlite3_vfs.xOpen]]
1215** ^SQLite guarantees that the zFilename parameter to xOpen
1216** is either a NULL pointer or string obtained
1217** from xFullPathname() with an optional suffix added.
1218** ^If a suffix is added to the zFilename parameter, it will
1219** consist of a single "-" character followed by no more than
1220** 11 alphanumeric and/or "-" characters.
1221** ^SQLite further guarantees that
1222** the string will be valid and unchanged until xClose() is
1223** called. Because of the previous sentence,
1224** the [sqlite3_file] can safely store a pointer to the
1225** filename if it needs to remember the filename for some reason.
1226** If the zFilename parameter to xOpen is a NULL pointer then xOpen
1227** must invent its own temporary name for the file. ^Whenever the
1228** xFilename parameter is NULL it will also be the case that the
1229** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
1231** The flags argument to xOpen() includes all bits set in
1232** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()]
1233** or [sqlite3_open16()] is used, then flags includes at least
1235** If xOpen() opens a file read-only then it sets *pOutFlags to
1236** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set.
1238** ^(SQLite will also add one of the following flags to the xOpen()
1239** call, depending on the object being opened:
1241** <ul>
1242** <li> [SQLITE_OPEN_MAIN_DB]
1244** <li> [SQLITE_OPEN_TEMP_DB]
1249** <li> [SQLITE_OPEN_WAL]
1250** </ul>)^
1252** The file I/O implementation can use the object type flags to
1253** change the way it deals with files. For example, an application
1254** that does not care about crash recovery or rollback might make
1255** the open of a journal file a no-op. Writes to this journal would
1256** also be no-ops, and any attempt to read the journal would return
1257** SQLITE_IOERR. Or the implementation might recognize that a database
1258** file will be doing page-aligned sector reads and writes in a random
1259** order and set up its I/O subsystem accordingly.
1261** SQLite might also add one of the following flags to the xOpen method:
1263** <ul>
1266** </ul>
1268** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
1269** deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE]
1270** will be set for TEMP databases and their journals, transient
1271** databases, and subjournals.
1273** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
1274** with the [SQLITE_OPEN_CREATE] flag, which are both directly
1275** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
1276** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the
1277** SQLITE_OPEN_CREATE, is used to indicate that file should always
1278** be created, and that it is an error if it already exists.
1279** It is <i>not</i> used to indicate the file should be opened
1280** for exclusive access.
1282** ^At least szOsFile bytes of memory are allocated by SQLite
1283** to hold the [sqlite3_file] structure passed as the third
1284** argument to xOpen. The xOpen method does not have to
1285** allocate the structure; it should just fill it in. Note that
1286** the xOpen method must set the sqlite3_file.pMethods to either
1287** a valid [sqlite3_io_methods] object or to NULL. xOpen must do
1288** this even if the open fails. SQLite expects that the sqlite3_file.pMethods
1289** element will be valid after xOpen returns regardless of the success
1290** or failure of the xOpen call.
1292** [[sqlite3_vfs.xAccess]]
1293** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
1294** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
1295** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
1296** to test whether a file is at least readable. The file can be a
1297** directory.
1299** ^SQLite will always allocate at least mxPathname+1 bytes for the
1300** output buffer xFullPathname. The exact size of the output buffer
1301** is also passed as a parameter to both methods. If the output buffer
1302** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
1303** handled as a fatal error by SQLite, vfs implementations should endeavor
1304** to prevent this by setting mxPathname to a sufficiently large value.
1306** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
1307** interfaces are not strictly a part of the filesystem, but they are
1308** included in the VFS structure for completeness.
1309** The xRandomness() function attempts to return nBytes bytes
1310** of good-quality randomness into zOut. The return value is
1311** the actual number of bytes of randomness obtained.
1312** The xSleep() method causes the calling thread to sleep for at
1313** least the number of microseconds given. ^The xCurrentTime()
1314** method returns a Julian Day Number for the current date and time as
1315** a floating point value.
1316** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
1317** Day Number multiplied by 86400000 (the number of milliseconds in
1318** a 24-hour day).
1319** ^SQLite will use the xCurrentTimeInt64() method to get the current
1320** date and time if that method is available (if iVersion is 2 or
1321** greater and the function pointer is not NULL) and will fall back
1322** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
1324** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
1325** are not used by the SQLite core. These optional interfaces are provided
1326** by some VFSes to facilitate testing of the VFS code. By overriding
1327** system calls with functions under its control, a test program can
1328** simulate faults and error conditions that would otherwise be difficult
1329** or impossible to induce. The set of system calls that can be overridden
1330** varies from one VFS to another, and from one version of the same VFS to the
1331** next. Applications that use these interfaces must be prepared for any
1332** or all of these interfaces to be NULL or for their behavior to change
1333** from one release to the next. Applications must not attempt to access
1334** any of these methods if the iVersion of the VFS is less than 3.
1336typedef struct sqlite3_vfs sqlite3_vfs;
1337typedef void (*sqlite3_syscall_ptr)(void);
1338struct sqlite3_vfs {
1339 int iVersion; /* Structure version number (currently 3) */
1340 int szOsFile; /* Size of subclassed sqlite3_file */
1341 int mxPathname; /* Maximum file pathname length */
1342 sqlite3_vfs *pNext; /* Next registered VFS */
1343 const char *zName; /* Name of this virtual file system */
1344 void *pAppData; /* Pointer to application-specific data */
1345 int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
1346 int flags, int *pOutFlags);
1347 int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
1348 int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
1349 int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
1350 void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
1351 void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
1352 void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
1353 void (*xDlClose)(sqlite3_vfs*, void*);
1354 int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
1355 int (*xSleep)(sqlite3_vfs*, int microseconds);
1356 int (*xCurrentTime)(sqlite3_vfs*, double*);
1357 int (*xGetLastError)(sqlite3_vfs*, int, char *);
1358 /*
1359 ** The methods above are in version 1 of the sqlite_vfs object
1360 ** definition. Those that follow are added in version 2 or later
1361 */
1362 int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
1363 /*
1364 ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
1365 ** Those below are for version 3 and greater.
1366 */
1367 int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
1368 sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
1369 const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
1370 /*
1371 ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
1372 ** New fields may be appended in future versions. The iVersion
1373 ** value will increment whenever this happens.
1374 */
1378** CAPI3REF: Flags for the xAccess VFS method
1380** These integer constants can be used as the third parameter to
1381** the xAccess method of an [sqlite3_vfs] object. They determine
1382** what kind of permissions the xAccess method is looking for.
1383** With SQLITE_ACCESS_EXISTS, the xAccess method
1384** simply checks whether the file exists.
1385** With SQLITE_ACCESS_READWRITE, the xAccess method
1386** checks whether the named directory is both readable and writable
1387** (in other words, if files can be added, removed, and renamed within
1388** the directory).
1389** The SQLITE_ACCESS_READWRITE constant is currently used only by the
1390** [temp_store_directory pragma], though this could change in a future
1391** release of SQLite.
1392** With SQLITE_ACCESS_READ, the xAccess method
1393** checks whether the file is readable. The SQLITE_ACCESS_READ constant is
1394** currently unused, though it might be used in a future release of
1395** SQLite.
1398#define SQLITE_ACCESS_READWRITE 1 /* Used by PRAGMA temp_store_directory */
1399#define SQLITE_ACCESS_READ 2 /* Unused */
1402** CAPI3REF: Flags for the xShmLock VFS method
1404** These integer constants define the various locking operations
1405** allowed by the xShmLock method of [sqlite3_io_methods]. The
1406** following are the only legal combinations of flags to the
1407** xShmLock method:
1409** <ul>
1414** </ul>
1416** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
1417** was given on the corresponding lock.
1419** The xShmLock method can transition between unlocked and SHARED or
1420** between unlocked and EXCLUSIVE. It cannot transition between SHARED
1421** and EXCLUSIVE.
1423#define SQLITE_SHM_UNLOCK 1
1424#define SQLITE_SHM_LOCK 2
1425#define SQLITE_SHM_SHARED 4
1429** CAPI3REF: Maximum xShmLock index
1431** The xShmLock method on [sqlite3_io_methods] may use values
1432** between 0 and this upper bound as its "offset" argument.
1433** The SQLite core will never attempt to acquire or release a
1434** lock outside of this range
1436#define SQLITE_SHM_NLOCK 8
1440** CAPI3REF: Initialize The SQLite Library
1442** ^The sqlite3_initialize() routine initializes the
1443** SQLite library. ^The sqlite3_shutdown() routine
1444** deallocates any resources that were allocated by sqlite3_initialize().
1445** These routines are designed to aid in process initialization and
1446** shutdown on embedded systems. Workstation applications using
1447** SQLite normally do not need to invoke either of these routines.
1449** A call to sqlite3_initialize() is an "effective" call if it is
1450** the first time sqlite3_initialize() is invoked during the lifetime of
1451** the process, or if it is the first time sqlite3_initialize() is invoked
1452** following a call to sqlite3_shutdown(). ^(Only an effective call
1453** of sqlite3_initialize() does any initialization. All other calls
1454** are harmless no-ops.)^
1456** A call to sqlite3_shutdown() is an "effective" call if it is the first
1457** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only
1458** an effective call to sqlite3_shutdown() does any deinitialization.
1459** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
1461** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
1462** is not. The sqlite3_shutdown() interface must only be called from a
1463** single thread. All open [database connections] must be closed and all
1464** other SQLite resources must be deallocated prior to invoking
1465** sqlite3_shutdown().
1467** Among other things, ^sqlite3_initialize() will invoke
1468** sqlite3_os_init(). Similarly, ^sqlite3_shutdown()
1469** will invoke sqlite3_os_end().
1471** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
1472** ^If for some reason, sqlite3_initialize() is unable to initialize
1473** the library (perhaps it is unable to allocate a needed resource such
1474** as a mutex) it returns an [error code] other than [SQLITE_OK].
1476** ^The sqlite3_initialize() routine is called internally by many other
1477** SQLite interfaces so that an application usually does not need to
1478** invoke sqlite3_initialize() directly. For example, [sqlite3_open()]
1479** calls sqlite3_initialize() so the SQLite library will be automatically
1480** initialized when [sqlite3_open()] is called if it has not be initialized
1481** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
1482** compile-time option, then the automatic calls to sqlite3_initialize()
1483** are omitted and the application must call sqlite3_initialize() directly
1484** prior to using any other SQLite interface. For maximum portability,
1485** it is recommended that applications always invoke sqlite3_initialize()
1486** directly prior to using any other SQLite interface. Future releases
1487** of SQLite may require this. In other words, the behavior exhibited
1488** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
1489** default behavior in some future release of SQLite.
1491** The sqlite3_os_init() routine does operating-system specific
1492** initialization of the SQLite library. The sqlite3_os_end()
1493** routine undoes the effect of sqlite3_os_init(). Typical tasks
1494** performed by these routines include allocation or deallocation
1495** of static resources, initialization of global variables,
1496** setting up a default [sqlite3_vfs] module, or setting up
1497** a default configuration using [sqlite3_config()].
1499** The application should never invoke either sqlite3_os_init()
1500** or sqlite3_os_end() directly. The application should only invoke
1501** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init()
1502** interface is called automatically by sqlite3_initialize() and
1503** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate
1504** implementations for sqlite3_os_init() and sqlite3_os_end()
1505** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
1506** When [custom builds | built for other platforms]
1507** (using the [SQLITE_OS_OTHER=1] compile-time
1508** option) the application must supply a suitable implementation for
1509** sqlite3_os_init() and sqlite3_os_end(). An application-supplied
1510** implementation of sqlite3_os_init() or sqlite3_os_end()
1511** must return [SQLITE_OK] on success and some other [error code] upon
1512** failure.
1514SQLITE_API int sqlite3_initialize(void);
1515SQLITE_API int sqlite3_shutdown(void);
1516SQLITE_API int sqlite3_os_init(void);
1517SQLITE_API int sqlite3_os_end(void);
1520** CAPI3REF: Configuring The SQLite Library
1522** The sqlite3_config() interface is used to make global configuration
1523** changes to SQLite in order to tune SQLite to the specific needs of
1524** the application. The default configuration is recommended for most
1525** applications and so this routine is usually not necessary. It is
1526** provided to support rare applications with unusual needs.
1528** <b>The sqlite3_config() interface is not threadsafe. The application
1529** must ensure that no other SQLite interfaces are invoked by other
1530** threads while sqlite3_config() is running.</b>
1532** The sqlite3_config() interface
1533** may only be invoked prior to library initialization using
1534** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
1535** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
1536** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
1537** Note, however, that ^sqlite3_config() can be called as part of the
1538** implementation of an application-defined [sqlite3_os_init()].
1540** The first argument to sqlite3_config() is an integer
1541** [configuration option] that determines
1542** what property of SQLite is to be configured. Subsequent arguments
1543** vary depending on the [configuration option]
1544** in the first argument.
1546** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
1547** ^If the option is unknown or SQLite is unable to set the option
1548** then this routine returns a non-zero [error code].
1550SQLITE_API int sqlite3_config(int, ...);
1553** CAPI3REF: Configure database connections
1554** METHOD: sqlite3
1556** The sqlite3_db_config() interface is used to make configuration
1557** changes to a [database connection]. The interface is similar to
1558** [sqlite3_config()] except that the changes apply to a single
1559** [database connection] (specified in the first argument).
1561** The second argument to sqlite3_db_config(D,V,...) is the
1562** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code
1563** that indicates what aspect of the [database connection] is being configured.
1564** Subsequent arguments vary depending on the configuration verb.
1566** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
1567** the call is considered successful.
1569SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
1572** CAPI3REF: Memory Allocation Routines
1574** An instance of this object defines the interface between SQLite
1575** and low-level memory allocation routines.
1577** This object is used in only one place in the SQLite interface.
1578** A pointer to an instance of this object is the argument to
1579** [sqlite3_config()] when the configuration option is
1581** By creating an instance of this object
1582** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
1583** during configuration, an application can specify an alternative
1584** memory allocation subsystem for SQLite to use for all of its
1585** dynamic memory needs.
1587** Note that SQLite comes with several [built-in memory allocators]
1588** that are perfectly adequate for the overwhelming majority of applications
1589** and that this object is only useful to a tiny minority of applications
1590** with specialized memory allocation requirements. This object is
1591** also used during testing of SQLite in order to specify an alternative
1592** memory allocator that simulates memory out-of-memory conditions in
1593** order to verify that SQLite recovers gracefully from such
1594** conditions.
1596** The xMalloc, xRealloc, and xFree methods must work like the
1597** malloc(), realloc() and free() functions from the standard C library.
1598** ^SQLite guarantees that the second argument to
1599** xRealloc is always a value returned by a prior call to xRoundup.
1601** xSize should return the allocated size of a memory allocation
1602** previously obtained from xMalloc or xRealloc. The allocated size
1603** is always at least as big as the requested size but may be larger.
1605** The xRoundup method returns what would be the allocated size of
1606** a memory allocation given a particular requested size. Most memory
1607** allocators round up memory allocations at least to the next multiple
1608** of 8. Some allocators round up to a larger multiple or to a power of 2.
1609** Every memory allocation request coming in through [sqlite3_malloc()]
1610** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0,
1611** that causes the corresponding memory allocation to fail.
1613** The xInit method initializes the memory allocator. For example,
1614** it might allocate any require mutexes or initialize internal data
1615** structures. The xShutdown method is invoked (indirectly) by
1616** [sqlite3_shutdown()] and should deallocate any resources acquired
1617** by xInit. The pAppData pointer is used as the only parameter to
1618** xInit and xShutdown.
1620** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
1621** the xInit method, so the xInit method need not be threadsafe. The
1622** xShutdown method is only called from [sqlite3_shutdown()] so it does
1623** not need to be threadsafe either. For all other methods, SQLite
1624** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
1625** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
1626** it is by default) and so the methods are automatically serialized.
1627** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
1628** methods must be threadsafe or else make their own arrangements for
1629** serialization.
1631** SQLite will never invoke xInit() more than once without an intervening
1632** call to xShutdown().
1634typedef struct sqlite3_mem_methods sqlite3_mem_methods;
1635struct sqlite3_mem_methods {
1636 void *(*xMalloc)(int); /* Memory allocation function */
1637 void (*xFree)(void*); /* Free a prior allocation */
1638 void *(*xRealloc)(void*,int); /* Resize an allocation */
1639 int (*xSize)(void*); /* Return the size of an allocation */
1640 int (*xRoundup)(int); /* Round up request size to allocation size */
1641 int (*xInit)(void*); /* Initialize the memory allocator */
1642 void (*xShutdown)(void*); /* Deinitialize the memory allocator */
1643 void *pAppData; /* Argument to xInit() and xShutdown() */
1647** CAPI3REF: Configuration Options
1648** KEYWORDS: {configuration option}
1650** These constants are the available integer configuration options that
1651** can be passed as the first argument to the [sqlite3_config()] interface.
1653** New configuration options may be added in future releases of SQLite.
1654** Existing configuration options might be discontinued. Applications
1655** should check the return code from [sqlite3_config()] to make sure that
1656** the call worked. The [sqlite3_config()] interface will return a
1657** non-zero [error code] if a discontinued or unsupported configuration option
1658** is invoked.
1660** <dl>
1662** <dd>There are no arguments to this option. ^This option sets the
1663** [threading mode] to Single-thread. In other words, it disables
1664** all mutexing and puts SQLite into a mode where it can only be used
1665** by a single thread. ^If SQLite is compiled with
1666** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1667** it is not possible to change the [threading mode] from its default
1668** value of Single-thread and so [sqlite3_config()] will return
1670** configuration option.</dd>
1673** <dd>There are no arguments to this option. ^This option sets the
1674** [threading mode] to Multi-thread. In other words, it disables
1675** mutexing on [database connection] and [prepared statement] objects.
1676** The application is responsible for serializing access to
1677** [database connections] and [prepared statements]. But other mutexes
1678** are enabled so that SQLite will be safe to use in a multi-threaded
1679** environment as long as no two threads attempt to use the same
1680** [database connection] at the same time. ^If SQLite is compiled with
1681** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1682** it is not possible to set the Multi-thread [threading mode] and
1683** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1684** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
1687** <dd>There are no arguments to this option. ^This option sets the
1688** [threading mode] to Serialized. In other words, this option enables
1689** all mutexes including the recursive
1690** mutexes on [database connection] and [prepared statement] objects.
1691** In this mode (which is the default when SQLite is compiled with
1692** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
1693** to [database connections] and [prepared statements] so that the
1694** application is free to use the same [database connection] or the
1695** same [prepared statement] in different threads at the same time.
1696** ^If SQLite is compiled with
1697** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1698** it is not possible to set the Serialized [threading mode] and
1699** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1700** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
1703** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is
1704** a pointer to an instance of the [sqlite3_mem_methods] structure.
1705** The argument specifies
1706** alternative low-level memory allocation routines to be used in place of
1707** the memory allocation routines built into SQLite.)^ ^SQLite makes
1708** its own private copy of the content of the [sqlite3_mem_methods] structure
1709** before the [sqlite3_config()] call returns.</dd>
1712** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
1713** is a pointer to an instance of the [sqlite3_mem_methods] structure.
1714** The [sqlite3_mem_methods]
1715** structure is filled with the currently defined memory allocation routines.)^
1716** This option can be used to overload the default memory allocation
1717** routines with a wrapper that simulations memory allocation failure or
1718** tracks memory usage, for example. </dd>
1721** <dd> ^The SQLITE_CONFIG_SMALL_MALLOC option takes single argument of
1722** type int, interpreted as a boolean, which if true provides a hint to
1723** SQLite that it should avoid large memory allocations if possible.
1724** SQLite will run faster if it is free to make large memory allocations,
1725** but some application might prefer to run slower in exchange for
1726** guarantees about memory fragmentation that are possible if large
1727** allocations are avoided. This hint is normally off.
1728** </dd>
1731** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
1732** interpreted as a boolean, which enables or disables the collection of
1733** memory allocation statistics. ^(When memory allocation statistics are
1734** disabled, the following SQLite interfaces become non-operational:
1735** <ul>
1736** <li> [sqlite3_memory_used()]
1737** <li> [sqlite3_memory_highwater()]
1738** <li> [sqlite3_soft_heap_limit64()]
1739** <li> [sqlite3_status64()]
1740** </ul>)^
1741** ^Memory allocation statistics are enabled by default unless SQLite is
1742** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
1743** allocation statistics are disabled by default.
1744** </dd>
1747** <dd> The SQLITE_CONFIG_SCRATCH option is no longer used.
1748** </dd>
1751** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
1752** that SQLite can use for the database page cache with the default page
1753** cache implementation.
1754** This configuration option is a no-op if an application-define page
1755** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
1756** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
1757** 8-byte aligned memory (pMem), the size of each page cache line (sz),
1758** and the number of cache lines (N).
1759** The sz argument should be the size of the largest database page
1760** (a power of two between 512 and 65536) plus some extra bytes for each
1761** page header. ^The number of extra bytes needed by the page header
1762** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
1763** ^It is harmless, apart from the wasted memory,
1764** for the sz parameter to be larger than necessary. The pMem
1765** argument must be either a NULL pointer or a pointer to an 8-byte
1766** aligned block of memory of at least sz*N bytes, otherwise
1767** subsequent behavior is undefined.
1768** ^When pMem is not NULL, SQLite will strive to use the memory provided
1769** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
1770** a page cache line is larger than sz bytes or if all of the pMem buffer
1771** is exhausted.
1772** ^If pMem is NULL and N is non-zero, then each database connection
1773** does an initial bulk allocation for page cache memory
1774** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
1775** of -1024*N bytes if N is negative, . ^If additional
1776** page cache memory is needed beyond what is provided by the initial
1777** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
1778** additional cache line. </dd>
1781** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer
1782** that SQLite will use for all of its dynamic memory allocation needs
1783** beyond those provided for by [SQLITE_CONFIG_PAGECACHE].
1784** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
1785** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
1786** [SQLITE_ERROR] if invoked otherwise.
1787** ^There are three arguments to SQLITE_CONFIG_HEAP:
1788** An 8-byte aligned pointer to the memory,
1789** the number of bytes in the memory buffer, and the minimum allocation size.
1790** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
1791** to using its default memory allocator (the system malloc() implementation),
1792** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the
1793** memory pointer is not NULL then the alternative memory
1794** allocator is engaged to handle all of SQLites memory allocation needs.
1795** The first pointer (the memory pointer) must be aligned to an 8-byte
1796** boundary or subsequent behavior of SQLite will be undefined.
1797** The minimum allocation size is capped at 2**12. Reasonable values
1798** for the minimum allocation size are 2**5 through 2**8.</dd>
1801** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
1802** pointer to an instance of the [sqlite3_mutex_methods] structure.
1803** The argument specifies alternative low-level mutex routines to be used
1804** in place the mutex routines built into SQLite.)^ ^SQLite makes a copy of
1805** the content of the [sqlite3_mutex_methods] structure before the call to
1806** [sqlite3_config()] returns. ^If SQLite is compiled with
1807** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1808** the entire mutexing subsystem is omitted from the build and hence calls to
1809** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
1810** return [SQLITE_ERROR].</dd>
1813** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
1814** is a pointer to an instance of the [sqlite3_mutex_methods] structure. The
1815** [sqlite3_mutex_methods]
1816** structure is filled with the currently defined mutex routines.)^
1817** This option can be used to overload the default mutex allocation
1818** routines with a wrapper used to track mutex usage for performance
1819** profiling or testing, for example. ^If SQLite is compiled with
1820** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1821** the entire mutexing subsystem is omitted from the build and hence calls to
1822** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
1823** return [SQLITE_ERROR].</dd>
1826** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
1827** the default size of lookaside memory on each [database connection].
1828** The first argument is the
1829** size of each lookaside buffer slot and the second is the number of
1830** slots allocated to each database connection.)^ ^(SQLITE_CONFIG_LOOKASIDE
1831** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
1832** option to [sqlite3_db_config()] can be used to change the lookaside
1833** configuration on individual connections.)^ </dd>
1836** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is
1837** a pointer to an [sqlite3_pcache_methods2] object. This object specifies
1838** the interface to a custom page cache implementation.)^
1839** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
1842** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
1843** is a pointer to an [sqlite3_pcache_methods2] object. SQLite copies of
1844** the current page cache implementation into that object.)^ </dd>
1847** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
1848** global [error log].
1849** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
1850** function with a call signature of void(*)(void*,int,const char*),
1851** and a pointer to void. ^If the function pointer is not NULL, it is
1852** invoked by [sqlite3_log()] to process each logging event. ^If the
1853** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
1854** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
1855** passed through as the first parameter to the application-defined logger
1856** function whenever that function is invoked. ^The second parameter to
1857** the logger function is a copy of the first parameter to the corresponding
1858** [sqlite3_log()] call and is intended to be a [result code] or an
1859** [extended result code]. ^The third parameter passed to the logger is
1860** log message after formatting via [sqlite3_snprintf()].
1861** The SQLite logging interface is not reentrant; the logger function
1862** supplied by the application must not invoke any SQLite interface.
1863** In a multi-threaded application, the application-defined logger
1864** function must be threadsafe. </dd>
1867** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
1868** If non-zero, then URI handling is globally enabled. If the parameter is zero,
1869** then URI handling is globally disabled.)^ ^If URI handling is globally
1870** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
1871** [sqlite3_open16()] or
1872** specified as part of [ATTACH] commands are interpreted as URIs, regardless
1873** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
1874** connection is opened. ^If it is globally disabled, filenames are
1875** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
1876** database connection is opened. ^(By default, URI handling is globally
1877** disabled. The default value may be changed by compiling with the
1878** [SQLITE_USE_URI] symbol defined.)^
1881** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
1882** argument which is interpreted as a boolean in order to enable or disable
1883** the use of covering indices for full table scans in the query optimizer.
1884** ^The default setting is determined
1885** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
1886** if that compile-time option is omitted.
1887** The ability to disable the use of covering indices for full table scans
1888** is because some incorrectly coded legacy applications might malfunction
1889** when the optimization is enabled. Providing the ability to
1890** disable the optimization allows the older, buggy application code to work
1891** without change even with newer versions of SQLite.
1895** <dd> These options are obsolete and should not be used by new code.
1896** They are retained for backwards compatibility but are now no-ops.
1897** </dd>
1901** <dd>This option is only available if sqlite is compiled with the
1902** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
1903** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
1904** The second should be of type (void*). The callback is invoked by the library
1905** in three separate circumstances, identified by the value passed as the
1906** fourth parameter. If the fourth parameter is 0, then the database connection
1907** passed as the second argument has just been opened. The third argument
1908** points to a buffer containing the name of the main database file. If the
1909** fourth parameter is 1, then the SQL statement that the third parameter
1910** points to has just been executed. Or, if the fourth parameter is 2, then
1911** the connection being passed as the second parameter is being closed. The
1912** third parameter is passed NULL In this case. An example of using this
1913** configuration option can be seen in the "test_sqllog.c" source file in
1914** the canonical SQLite source tree.</dd>
1918** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
1919** that are the default mmap size limit (the default setting for
1920** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
1921** ^The default setting can be overridden by each database connection using
1922** either the [PRAGMA mmap_size] command, or by using the
1923** [SQLITE_FCNTL_MMAP_SIZE] file control. ^(The maximum allowed mmap size
1924** will be silently truncated if necessary so that it does not exceed the
1925** compile-time maximum mmap size set by the
1926** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
1927** ^If either argument to this option is negative, then that argument is
1928** changed to its compile-time default.
1932** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
1933** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
1934** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
1935** that specifies the maximum size of the created heap.
1939** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
1940** is a pointer to an integer and writes into that integer the number of extra
1941** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
1942** The amount of extra space required can change depending on the compiler,
1943** target platform, and SQLite version.
1947** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
1948** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
1949** sorter to that integer. The default minimum PMA Size is set by the
1950** [SQLITE_SORTER_PMASZ] compile-time option. New threads are launched
1951** to help with sort operations when multithreaded sorting
1952** is enabled (using the [PRAGMA threads] command) and the amount of content
1953** to be sorted exceeds the page size times the minimum of the
1954** [PRAGMA cache_size] setting and this value.
1958** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
1959** becomes the [statement journal] spill-to-disk threshold.
1960** [Statement journals] are held in memory until their size (in bytes)
1961** exceeds this threshold, at which point they are written to disk.
1962** Or if the threshold is -1, statement journals are always held
1963** exclusively in memory.
1964** Since many statement journals never become large, setting the spill
1965** threshold to a value such as 64KiB can greatly reduce the amount of
1966** I/O required to support statement rollback.
1967** The default value for this setting is controlled by the
1968** [SQLITE_STMTJRNL_SPILL] compile-time option.
1972** <dd>The SQLITE_CONFIG_SORTERREF_SIZE option accepts a single parameter
1973** of type (int) - the new value of the sorter-reference size threshold.
1974** Usually, when SQLite uses an external sort to order records according
1975** to an ORDER BY clause, all fields required by the caller are present in the
1976** sorted records. However, if SQLite determines based on the declared type
1977** of a table column that its values are likely to be very large - larger
1978** than the configured sorter-reference size threshold - then a reference
1979** is stored in each sorted record and the required column values loaded
1980** from the database as records are returned in sorted order. The default
1981** value for this option is to never use this optimization. Specifying a
1982** negative value for this option restores the default behaviour.
1983** This option is only available if SQLite is compiled with the
1984** [SQLITE_ENABLE_SORTER_REFERENCES] compile-time option.
1988** <dd>The SQLITE_CONFIG_MEMDB_MAXSIZE option accepts a single parameter
1989** [sqlite3_int64] parameter which is the default maximum size for an in-memory
1990** database created using [sqlite3_deserialize()]. This default maximum
1991** size can be adjusted up or down for individual databases using the
1992** [SQLITE_FCNTL_SIZE_LIMIT] [sqlite3_file_control|file-control]. If this
1993** configuration setting is never used, then the default maximum is determined
1994** by the [SQLITE_MEMDB_DEFAULT_MAXSIZE] compile-time option. If that
1995** compile-time option is not set, then the default maximum is 1073741824.
1996** </dl>
1998#define SQLITE_CONFIG_SINGLETHREAD 1 /* nil */
1999#define SQLITE_CONFIG_MULTITHREAD 2 /* nil */
2000#define SQLITE_CONFIG_SERIALIZED 3 /* nil */
2001#define SQLITE_CONFIG_MALLOC 4 /* sqlite3_mem_methods* */
2002#define SQLITE_CONFIG_GETMALLOC 5 /* sqlite3_mem_methods* */
2003#define SQLITE_CONFIG_SCRATCH 6 /* No longer used */
2004#define SQLITE_CONFIG_PAGECACHE 7 /* void*, int sz, int N */
2005#define SQLITE_CONFIG_HEAP 8 /* void*, int nByte, int min */
2006#define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */
2007#define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */
2008#define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */
2009/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
2010#define SQLITE_CONFIG_LOOKASIDE 13 /* int int */
2011#define SQLITE_CONFIG_PCACHE 14 /* no-op */
2012#define SQLITE_CONFIG_GETPCACHE 15 /* no-op */
2013#define SQLITE_CONFIG_LOG 16 /* xFunc, void* */
2014#define SQLITE_CONFIG_URI 17 /* int */
2015#define SQLITE_CONFIG_PCACHE2 18 /* sqlite3_pcache_methods2* */
2016#define SQLITE_CONFIG_GETPCACHE2 19 /* sqlite3_pcache_methods2* */
2017#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20 /* int */
2018#define SQLITE_CONFIG_SQLLOG 21 /* xSqllog, void* */
2019#define SQLITE_CONFIG_MMAP_SIZE 22 /* sqlite3_int64, sqlite3_int64 */
2020#define SQLITE_CONFIG_WIN32_HEAPSIZE 23 /* int nByte */
2021#define SQLITE_CONFIG_PCACHE_HDRSZ 24 /* int *psz */
2022#define SQLITE_CONFIG_PMASZ 25 /* unsigned int szPma */
2023#define SQLITE_CONFIG_STMTJRNL_SPILL 26 /* int nByte */
2024#define SQLITE_CONFIG_SMALL_MALLOC 27 /* boolean */
2025#define SQLITE_CONFIG_SORTERREF_SIZE 28 /* int nByte */
2026#define SQLITE_CONFIG_MEMDB_MAXSIZE 29 /* sqlite3_int64 */
2029** CAPI3REF: Database Connection Configuration Options
2031** These constants are the available integer configuration options that
2032** can be passed as the second argument to the [sqlite3_db_config()] interface.
2034** New configuration options may be added in future releases of SQLite.
2035** Existing configuration options might be discontinued. Applications
2036** should check the return code from [sqlite3_db_config()] to make sure that
2037** the call worked. ^The [sqlite3_db_config()] interface will return a
2038** non-zero [error code] if a discontinued or unsupported configuration option
2039** is invoked.
2041** <dl>
2044** <dd> ^This option takes three additional arguments that determine the
2045** [lookaside memory allocator] configuration for the [database connection].
2046** ^The first argument (the third parameter to [sqlite3_db_config()] is a
2047** pointer to a memory buffer to use for lookaside memory.
2048** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
2049** may be NULL in which case SQLite will allocate the
2050** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
2051** size of each lookaside buffer slot. ^The third argument is the number of
2052** slots. The size of the buffer in the first argument must be greater than
2053** or equal to the product of the second and third arguments. The buffer
2054** must be aligned to an 8-byte boundary. ^If the second argument to
2055** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
2056** rounded down to the next smaller multiple of 8. ^(The lookaside memory
2057** configuration for a database connection can only be changed when that
2058** connection is not currently using lookaside memory, or in other words
2059** when the "current value" returned by
2060** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
2061** Any attempt to change the lookaside memory configuration when lookaside
2062** memory is in use leaves the configuration unchanged and returns
2063** [SQLITE_BUSY].)^</dd>
2067** <dd> ^This option is used to enable or disable the enforcement of
2068** [foreign key constraints]. There should be two additional arguments.
2069** The first argument is an integer which is 0 to disable FK enforcement,
2070** positive to enable FK enforcement or negative to leave FK enforcement
2071** unchanged. The second parameter is a pointer to an integer into which
2072** is written 0 or 1 to indicate whether FK enforcement is off or on
2073** following this call. The second parameter may be a NULL pointer, in
2074** which case the FK enforcement setting is not reported back. </dd>
2078** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
2079** There should be two additional arguments.
2080** The first argument is an integer which is 0 to disable triggers,
2081** positive to enable triggers or negative to leave the setting unchanged.
2082** The second parameter is a pointer to an integer into which
2083** is written 0 or 1 to indicate whether triggers are disabled or enabled
2084** following this call. The second parameter may be a NULL pointer, in
2085** which case the trigger setting is not reported back. </dd>
2089** <dd> ^This option is used to enable or disable the two-argument
2090** version of the [fts3_tokenizer()] function which is part of the
2091** [FTS3] full-text search engine extension.
2092** There should be two additional arguments.
2093** The first argument is an integer which is 0 to disable fts3_tokenizer() or
2094** positive to enable fts3_tokenizer() or negative to leave the setting
2095** unchanged.
2096** The second parameter is a pointer to an integer into which
2097** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
2098** following this call. The second parameter may be a NULL pointer, in
2099** which case the new setting is not reported back. </dd>
2103** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
2104** interface independently of the [load_extension()] SQL function.
2105** The [sqlite3_enable_load_extension()] API enables or disables both the
2106** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
2107** There should be two additional arguments.
2108** When the first argument to this interface is 1, then only the C-API is
2109** enabled and the SQL function remains disabled. If the first argument to
2110** this interface is 0, then both the C-API and the SQL function are disabled.
2111** If the first argument is -1, then no changes are made to state of either the
2112** C-API or the SQL function.
2113** The second parameter is a pointer to an integer into which
2114** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
2115** is disabled or enabled following this call. The second parameter may
2116** be a NULL pointer, in which case the new setting is not reported back.
2117** </dd>
2120** <dd> ^This option is used to change the name of the "main" database
2121** schema. ^The sole argument is a pointer to a constant UTF8 string
2122** which will become the new schema name in place of "main". ^SQLite
2123** does not make a copy of the new main schema name string, so the application
2124** must ensure that the argument passed into this DBCONFIG option is unchanged
2125** until after the database connection closes.
2126** </dd>
2130** <dd> Usually, when a database in wal mode is closed or detached from a
2131** database handle, SQLite checks if this will mean that there are now no
2132** connections at all to the database. If so, it performs a checkpoint
2133** operation before closing the connection. This option may be used to
2134** override this behaviour. The first parameter passed to this operation
2135** is an integer - positive to disable checkpoints-on-close, or zero (the
2136** default) to enable them, and negative to leave the setting unchanged.
2137** The second parameter is a pointer to an integer
2138** into which is written 0 or 1 to indicate whether checkpoints-on-close
2139** have been disabled - 0 if they are not disabled, 1 if they are.
2140** </dd>
2143** <dd>^(The SQLITE_DBCONFIG_ENABLE_QPSG option activates or deactivates
2144** the [query planner stability guarantee] (QPSG). When the QPSG is active,
2145** a single SQL query statement will always use the same algorithm regardless
2146** of values of [bound parameters].)^ The QPSG disables some query optimizations
2147** that look at the values of bound parameters, which can make some queries
2148** slower. But the QPSG has the advantage of more predictable behavior. With
2149** the QPSG active, SQLite will always use the same query plan in the field as
2150** was used during testing in the lab.
2151** The first argument to this setting is an integer which is 0 to disable
2152** the QPSG, positive to enable QPSG, or negative to leave the setting
2153** unchanged. The second parameter is a pointer to an integer into which
2154** is written 0 or 1 to indicate whether the QPSG is disabled or enabled
2155** following this call.
2156** </dd>
2159** <dd> By default, the output of EXPLAIN QUERY PLAN commands does not
2160** include output for any operations performed by trigger programs. This
2161** option is used to set or clear (the default) a flag that governs this
2162** behavior. The first parameter passed to this operation is an integer -
2163** positive to enable output for trigger programs, or zero to disable it,
2164** or negative to leave the setting unchanged.
2165** The second parameter is a pointer to an integer into which is written
2166** 0 or 1 to indicate whether output-for-triggers has been disabled - 0 if
2167** it is not disabled, 1 if it is.
2168** </dd>
2171** <dd> Set the SQLITE_DBCONFIG_RESET_DATABASE flag and then run
2172** [VACUUM] in order to reset a database back to an empty database
2173** with no schema and no content. The following process works even for
2174** a badly corrupted database file:
2175** <ol>
2176** <li> If the database connection is newly opened, make sure it has read the
2177** database schema by preparing then discarding some query against the
2178** database, or calling sqlite3_table_column_metadata(), ignoring any
2179** errors. This step is only necessary if the application desires to keep
2180** the database in WAL mode after the reset if it was in WAL mode before
2181** the reset.
2182** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
2183** <li> [sqlite3_exec](db, "[VACUUM]", 0, 0, 0);
2184** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
2185** </ol>
2186** Because resetting a database is destructive and irreversible, the
2187** process requires the use of this obscure API and multiple steps to help
2188** ensure that it does not happen by accident.
2191** <dd>The SQLITE_DBCONFIG_DEFENSIVE option activates or deactivates the
2192** "defensive" flag for a database connection. When the defensive
2193** flag is enabled, language features that allow ordinary SQL to
2194** deliberately corrupt the database file are disabled. The disabled
2195** features include but are not limited to the following:
2196** <ul>
2197** <li> The [PRAGMA writable_schema=ON] statement.
2198** <li> Writes to the [sqlite_dbpage] virtual table.
2199** <li> Direct writes to [shadow tables].
2200** </ul>
2201** </dd>
2202** </dl>
2204#define SQLITE_DBCONFIG_MAINDBNAME 1000 /* const char* */
2205#define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */
2206#define SQLITE_DBCONFIG_ENABLE_FKEY 1002 /* int int* */
2207#define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 /* int int* */
2208#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
2209#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
2210#define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE 1006 /* int int* */
2211#define SQLITE_DBCONFIG_ENABLE_QPSG 1007 /* int int* */
2212#define SQLITE_DBCONFIG_TRIGGER_EQP 1008 /* int int* */
2213#define SQLITE_DBCONFIG_RESET_DATABASE 1009 /* int int* */
2214#define SQLITE_DBCONFIG_DEFENSIVE 1010 /* int int* */
2215#define SQLITE_DBCONFIG_MAX 1010 /* Largest DBCONFIG */
2218** CAPI3REF: Enable Or Disable Extended Result Codes
2219** METHOD: sqlite3
2221** ^The sqlite3_extended_result_codes() routine enables or disables the
2222** [extended result codes] feature of SQLite. ^The extended result
2223** codes are disabled by default for historical compatibility.
2225SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
2228** CAPI3REF: Last Insert Rowid
2229** METHOD: sqlite3
2231** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
2232** has a unique 64-bit signed
2233** integer key called the [ROWID | "rowid"]. ^The rowid is always available
2234** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
2235** names are not also used by explicitly declared columns. ^If
2236** the table has a column of type [INTEGER PRIMARY KEY] then that column
2237** is another alias for the rowid.
2239** ^The sqlite3_last_insert_rowid(D) interface usually returns the [rowid] of
2240** the most recent successful [INSERT] into a rowid table or [virtual table]
2241** on database connection D. ^Inserts into [WITHOUT ROWID] tables are not
2242** recorded. ^If no successful [INSERT]s into rowid tables have ever occurred
2243** on the database connection D, then sqlite3_last_insert_rowid(D) returns
2244** zero.
2246** As well as being set automatically as rows are inserted into database
2247** tables, the value returned by this function may be set explicitly by
2248** [sqlite3_set_last_insert_rowid()]
2250** Some virtual table implementations may INSERT rows into rowid tables as
2251** part of committing a transaction (e.g. to flush data accumulated in memory
2252** to disk). In this case subsequent calls to this function return the rowid
2253** associated with these internal INSERT operations, which leads to
2254** unintuitive results. Virtual table implementations that do write to rowid
2255** tables in this way can avoid this problem by restoring the original
2256** rowid value using [sqlite3_set_last_insert_rowid()] before returning
2257** control to the user.
2259** ^(If an [INSERT] occurs within a trigger then this routine will
2260** return the [rowid] of the inserted row as long as the trigger is
2261** running. Once the trigger program ends, the value returned
2262** by this routine reverts to what it was before the trigger was fired.)^
2264** ^An [INSERT] that fails due to a constraint violation is not a
2265** successful [INSERT] and does not change the value returned by this
2267** and INSERT OR ABORT make no changes to the return value of this
2268** routine when their insertion fails. ^(When INSERT OR REPLACE
2269** encounters a constraint violation, it does not fail. The
2270** INSERT continues to completion after deleting rows that caused
2271** the constraint problem so INSERT OR REPLACE will always change
2272** the return value of this interface.)^
2274** ^For the purposes of this routine, an [INSERT] is considered to
2275** be successful even if it is subsequently rolled back.
2277** This function is accessible to SQL statements via the
2278** [last_insert_rowid() SQL function].
2280** If a separate thread performs a new [INSERT] on the same
2281** database connection while the [sqlite3_last_insert_rowid()]
2282** function is running and thus changes the last insert [rowid],
2283** then the value returned by [sqlite3_last_insert_rowid()] is
2284** unpredictable and might not equal either the old or the new
2285** last insert [rowid].
2287SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
2290** CAPI3REF: Set the Last Insert Rowid value.
2291** METHOD: sqlite3
2293** The sqlite3_set_last_insert_rowid(D, R) method allows the application to
2294** set the value returned by calling sqlite3_last_insert_rowid(D) to R
2295** without inserting a row into the database.
2297SQLITE_API void sqlite3_set_last_insert_rowid(sqlite3*,sqlite3_int64);
2300** CAPI3REF: Count The Number Of Rows Modified
2301** METHOD: sqlite3
2303** ^This function returns the number of rows modified, inserted or
2304** deleted by the most recently completed INSERT, UPDATE or DELETE
2305** statement on the database connection specified by the only parameter.
2306** ^Executing any other type of SQL statement does not modify the value
2307** returned by this function.
2309** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
2310** considered - auxiliary changes caused by [CREATE TRIGGER | triggers],
2311** [foreign key actions] or [REPLACE] constraint resolution are not counted.
2313** Changes to a view that are intercepted by
2314** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value
2315** returned by sqlite3_changes() immediately after an INSERT, UPDATE or
2316** DELETE statement run on a view is always zero. Only changes made to real
2317** tables are counted.
2319** Things are more complicated if the sqlite3_changes() function is
2320** executed while a trigger program is running. This may happen if the
2321** program uses the [changes() SQL function], or if some other callback
2322** function invokes sqlite3_changes() directly. Essentially:
2324** <ul>
2325** <li> ^(Before entering a trigger program the value returned by
2326** sqlite3_changes() function is saved. After the trigger program
2327** has finished, the original value is restored.)^
2329** <li> ^(Within a trigger program each INSERT, UPDATE and DELETE
2330** statement sets the value returned by sqlite3_changes()
2331** upon completion as normal. Of course, this value will not include
2332** any changes performed by sub-triggers, as the sqlite3_changes()
2333** value will be saved and restored after each sub-trigger has run.)^
2334** </ul>
2336** ^This means that if the changes() SQL function (or similar) is used
2337** by the first INSERT, UPDATE or DELETE statement within a trigger, it
2338** returns the value as set when the calling statement began executing.
2339** ^If it is used by the second or subsequent such statement within a trigger
2340** program, the value returned reflects the number of rows modified by the
2341** previous INSERT, UPDATE or DELETE statement within the same trigger.
2343** If a separate thread makes changes on the same database connection
2344** while [sqlite3_changes()] is running then the value returned
2345** is unpredictable and not meaningful.
2347** See also:
2348** <ul>
2349** <li> the [sqlite3_total_changes()] interface
2350** <li> the [count_changes pragma]
2351** <li> the [changes() SQL function]
2352** <li> the [data_version pragma]
2353** </ul>
2355SQLITE_API int sqlite3_changes(sqlite3*);
2358** CAPI3REF: Total Number Of Rows Modified
2359** METHOD: sqlite3
2361** ^This function returns the total number of rows inserted, modified or
2362** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
2363** since the database connection was opened, including those executed as
2364** part of trigger programs. ^Executing any other type of SQL statement
2365** does not affect the value returned by sqlite3_total_changes().
2367** ^Changes made as part of [foreign key actions] are included in the
2368** count, but those made as part of REPLACE constraint resolution are
2369** not. ^Changes to a view that are intercepted by INSTEAD OF triggers
2370** are not counted.
2372** The [sqlite3_total_changes(D)] interface only reports the number
2373** of rows that changed due to SQL statement run against database
2374** connection D. Any changes by other database connections are ignored.
2375** To detect changes against a database file from other database
2376** connections use the [PRAGMA data_version] command or the
2377** [SQLITE_FCNTL_DATA_VERSION] [file control].
2379** If a separate thread makes changes on the same database connection
2380** while [sqlite3_total_changes()] is running then the value
2381** returned is unpredictable and not meaningful.
2383** See also:
2384** <ul>
2385** <li> the [sqlite3_changes()] interface
2386** <li> the [count_changes pragma]
2387** <li> the [changes() SQL function]
2388** <li> the [data_version pragma]
2389** <li> the [SQLITE_FCNTL_DATA_VERSION] [file control]
2390** </ul>
2392SQLITE_API int sqlite3_total_changes(sqlite3*);
2395** CAPI3REF: Interrupt A Long-Running Query
2396** METHOD: sqlite3
2398** ^This function causes any pending database operation to abort and
2399** return at its earliest opportunity. This routine is typically
2400** called in response to a user action such as pressing "Cancel"
2401** or Ctrl-C where the user wants a long query operation to halt
2402** immediately.
2404** ^It is safe to call this routine from a thread different from the
2405** thread that is currently running the database operation. But it
2406** is not safe to call this routine with a [database connection] that
2407** is closed or might close before sqlite3_interrupt() returns.
2409** ^If an SQL operation is very nearly finished at the time when
2410** sqlite3_interrupt() is called, then it might not have an opportunity
2411** to be interrupted and might continue to completion.
2413** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
2414** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
2415** that is inside an explicit transaction, then the entire transaction
2416** will be rolled back automatically.
2418** ^The sqlite3_interrupt(D) call is in effect until all currently running
2419** SQL statements on [database connection] D complete. ^Any new SQL statements
2420** that are started after the sqlite3_interrupt() call and before the
2421** running statements reaches zero are interrupted as if they had been
2422** running prior to the sqlite3_interrupt() call. ^New SQL statements
2423** that are started after the running statement count reaches zero are
2424** not effected by the sqlite3_interrupt().
2425** ^A call to sqlite3_interrupt(D) that occurs when there are no running
2426** SQL statements is a no-op and has no effect on SQL statements
2427** that are started after the sqlite3_interrupt() call returns.
2429SQLITE_API void sqlite3_interrupt(sqlite3*);
2432** CAPI3REF: Determine If An SQL Statement Is Complete
2434** These routines are useful during command-line input to determine if the
2435** currently entered text seems to form a complete SQL statement or
2436** if additional input is needed before sending the text into
2437** SQLite for parsing. ^These routines return 1 if the input string
2438** appears to be a complete SQL statement. ^A statement is judged to be
2439** complete if it ends with a semicolon token and is not a prefix of a
2440** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within
2441** string literals or quoted identifier names or comments are not
2442** independent tokens (they are part of the token in which they are
2443** embedded) and thus do not count as a statement terminator. ^Whitespace
2444** and comments that follow the final semicolon are ignored.
2446** ^These routines return 0 if the statement is incomplete. ^If a
2447** memory allocation fails, then SQLITE_NOMEM is returned.
2449** ^These routines do not parse the SQL statements thus
2450** will not detect syntactically incorrect SQL.
2452** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior
2453** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
2454** automatically by sqlite3_complete16(). If that initialization fails,
2455** then the return value from sqlite3_complete16() will be non-zero
2456** regardless of whether or not the input SQL is complete.)^
2458** The input to [sqlite3_complete()] must be a zero-terminated
2459** UTF-8 string.
2461** The input to [sqlite3_complete16()] must be a zero-terminated
2462** UTF-16 string in native byte order.
2464SQLITE_API int sqlite3_complete(const char *sql);
2465SQLITE_API int sqlite3_complete16(const void *sql);
2468** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
2469** KEYWORDS: {busy-handler callback} {busy handler}
2470** METHOD: sqlite3
2472** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
2473** that might be invoked with argument P whenever
2474** an attempt is made to access a database table associated with
2475** [database connection] D when another thread
2476** or process has the table locked.
2477** The sqlite3_busy_handler() interface is used to implement
2478** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
2480** ^If the busy callback is NULL, then [SQLITE_BUSY]
2481** is returned immediately upon encountering the lock. ^If the busy callback
2482** is not NULL, then the callback might be invoked with two arguments.
2484** ^The first argument to the busy handler is a copy of the void* pointer which
2485** is the third argument to sqlite3_busy_handler(). ^The second argument to
2486** the busy handler callback is the number of times that the busy handler has
2487** been invoked previously for the same locking event. ^If the
2488** busy callback returns 0, then no additional attempts are made to
2489** access the database and [SQLITE_BUSY] is returned
2490** to the application.
2491** ^If the callback returns non-zero, then another attempt
2492** is made to access the database and the cycle repeats.
2494** The presence of a busy handler does not guarantee that it will be invoked
2495** when there is lock contention. ^If SQLite determines that invoking the busy
2496** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
2497** to the application instead of invoking the
2498** busy handler.
2499** Consider a scenario where one process is holding a read lock that
2500** it is trying to promote to a reserved lock and
2501** a second process is holding a reserved lock that it is trying
2502** to promote to an exclusive lock. The first process cannot proceed
2503** because it is blocked by the second and the second process cannot
2504** proceed because it is blocked by the first. If both processes
2505** invoke the busy handlers, neither will make any progress. Therefore,
2506** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
2507** will induce the first process to release its read lock and allow
2508** the second process to proceed.
2510** ^The default busy callback is NULL.
2512** ^(There can only be a single busy handler defined for each
2513** [database connection]. Setting a new busy handler clears any
2514** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()]
2515** or evaluating [PRAGMA busy_timeout=N] will change the
2516** busy handler and thus clear any previously set busy handler.
2518** The busy callback should not take any actions which modify the
2519** database connection that invoked the busy handler. In other words,
2520** the busy handler is not reentrant. Any such actions
2521** result in undefined behavior.
2523** A busy handler must not close the database connection
2524** or [prepared statement] that invoked the busy handler.
2526SQLITE_API int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
2529** CAPI3REF: Set A Busy Timeout
2530** METHOD: sqlite3
2532** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
2533** for a specified amount of time when a table is locked. ^The handler
2534** will sleep multiple times until at least "ms" milliseconds of sleeping
2535** have accumulated. ^After at least "ms" milliseconds of sleeping,
2536** the handler returns 0 which causes [sqlite3_step()] to return
2537** [SQLITE_BUSY].
2539** ^Calling this routine with an argument less than or equal to zero
2540** turns off all busy handlers.
2542** ^(There can only be a single busy handler for a particular
2543** [database connection] at any given moment. If another busy handler
2544** was defined (using [sqlite3_busy_handler()]) prior to calling
2545** this routine, that other busy handler is cleared.)^
2547** See also: [PRAGMA busy_timeout]
2549SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
2552** CAPI3REF: Convenience Routines For Running Queries
2553** METHOD: sqlite3
2555** This is a legacy interface that is preserved for backwards compatibility.
2556** Use of this interface is not recommended.
2558** Definition: A <b>result table</b> is memory data structure created by the
2559** [sqlite3_get_table()] interface. A result table records the
2560** complete query results from one or more queries.
2562** The table conceptually has a number of rows and columns. But
2563** these numbers are not part of the result table itself. These
2564** numbers are obtained separately. Let N be the number of rows
2565** and M be the number of columns.
2567** A result table is an array of pointers to zero-terminated UTF-8 strings.
2568** There are (N+1)*M elements in the array. The first M pointers point
2569** to zero-terminated strings that contain the names of the columns.
2570** The remaining entries all point to query results. NULL values result
2571** in NULL pointers. All other values are in their UTF-8 zero-terminated
2572** string representation as returned by [sqlite3_column_text()].
2574** A result table might consist of one or more memory allocations.
2575** It is not safe to pass a result table directly to [sqlite3_free()].
2576** A result table should be deallocated using [sqlite3_free_table()].
2578** ^(As an example of the result table format, suppose a query result
2579** is as follows:
2581** <blockquote><pre>
2582** Name | Age
2583** -----------------------
2584** Alice | 43
2585** Bob | 28
2586** Cindy | 21
2587** </pre></blockquote>
2589** There are two column (M==2) and three rows (N==3). Thus the
2590** result table has 8 entries. Suppose the result table is stored
2591** in an array names azResult. Then azResult holds this content:
2593** <blockquote><pre>
2594** azResult&#91;0] = "Name";
2595** azResult&#91;1] = "Age";
2596** azResult&#91;2] = "Alice";
2597** azResult&#91;3] = "43";
2598** azResult&#91;4] = "Bob";
2599** azResult&#91;5] = "28";
2600** azResult&#91;6] = "Cindy";
2601** azResult&#91;7] = "21";
2602** </pre></blockquote>)^
2604** ^The sqlite3_get_table() function evaluates one or more
2605** semicolon-separated SQL statements in the zero-terminated UTF-8
2606** string of its 2nd parameter and returns a result table to the
2607** pointer given in its 3rd parameter.
2609** After the application has finished with the result from sqlite3_get_table(),
2610** it must pass the result table pointer to sqlite3_free_table() in order to
2611** release the memory that was malloced. Because of the way the
2612** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
2613** function must not try to call [sqlite3_free()] directly. Only
2614** [sqlite3_free_table()] is able to release the memory properly and safely.
2616** The sqlite3_get_table() interface is implemented as a wrapper around
2617** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access
2618** to any internal data structures of SQLite. It uses only the public
2619** interface defined here. As a consequence, errors that occur in the
2620** wrapper layer outside of the internal [sqlite3_exec()] call are not
2621** reflected in subsequent calls to [sqlite3_errcode()] or
2622** [sqlite3_errmsg()].
2624SQLITE_API int sqlite3_get_table(
2625 sqlite3 *db, /* An open database */
2626 const char *zSql, /* SQL to be evaluated */
2627 char ***pazResult, /* Results of the query */
2628 int *pnRow, /* Number of result rows written here */
2629 int *pnColumn, /* Number of result columns written here */
2630 char **pzErrmsg /* Error msg written here */
2632SQLITE_API void sqlite3_free_table(char **result);
2635** CAPI3REF: Formatted String Printing Functions
2637** These routines are work-alikes of the "printf()" family of functions
2638** from the standard C library.
2639** These routines understand most of the common formatting options from
2640** the standard library printf()
2641** plus some additional non-standard formats ([%q], [%Q], [%w], and [%z]).
2642** See the [built-in printf()] documentation for details.
2644** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
2645** results into memory obtained from [sqlite3_malloc64()].
2646** The strings returned by these two routines should be
2647** released by [sqlite3_free()]. ^Both routines return a
2648** NULL pointer if [sqlite3_malloc64()] is unable to allocate enough
2649** memory to hold the resulting string.
2651** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
2652** the standard C library. The result is written into the
2653** buffer supplied as the second parameter whose size is given by
2654** the first parameter. Note that the order of the
2655** first two parameters is reversed from snprintf().)^ This is an
2656** historical accident that cannot be fixed without breaking
2657** backwards compatibility. ^(Note also that sqlite3_snprintf()
2658** returns a pointer to its buffer instead of the number of
2659** characters actually written into the buffer.)^ We admit that
2660** the number of characters written would be a more useful return
2661** value but we cannot change the implementation of sqlite3_snprintf()
2662** now without breaking compatibility.
2664** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
2665** guarantees that the buffer is always zero-terminated. ^The first
2666** parameter "n" is the total size of the buffer, including space for
2667** the zero terminator. So the longest string that can be completely
2668** written will be n-1 characters.
2670** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
2672** See also: [built-in printf()], [printf() SQL function]
2674SQLITE_API char *sqlite3_mprintf(const char*,...);
2675SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
2676SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
2677SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
2680** CAPI3REF: Memory Allocation Subsystem
2682** The SQLite core uses these three routines for all of its own
2683** internal memory allocation needs. "Core" in the previous sentence
2684** does not include operating-system specific VFS implementation. The
2685** Windows VFS uses native malloc() and free() for some operations.
2687** ^The sqlite3_malloc() routine returns a pointer to a block
2688** of memory at least N bytes in length, where N is the parameter.
2689** ^If sqlite3_malloc() is unable to obtain sufficient free
2690** memory, it returns a NULL pointer. ^If the parameter N to
2691** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
2692** a NULL pointer.
2694** ^The sqlite3_malloc64(N) routine works just like
2695** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
2696** of a signed 32-bit integer.
2698** ^Calling sqlite3_free() with a pointer previously returned
2699** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
2700** that it might be reused. ^The sqlite3_free() routine is
2701** a no-op if is called with a NULL pointer. Passing a NULL pointer
2702** to sqlite3_free() is harmless. After being freed, memory
2703** should neither be read nor written. Even reading previously freed
2704** memory might result in a segmentation fault or other severe error.
2705** Memory corruption, a segmentation fault, or other severe error
2706** might result if sqlite3_free() is called with a non-NULL pointer that
2707** was not obtained from sqlite3_malloc() or sqlite3_realloc().
2709** ^The sqlite3_realloc(X,N) interface attempts to resize a
2710** prior memory allocation X to be at least N bytes.
2711** ^If the X parameter to sqlite3_realloc(X,N)
2712** is a NULL pointer then its behavior is identical to calling
2713** sqlite3_malloc(N).
2714** ^If the N parameter to sqlite3_realloc(X,N) is zero or
2715** negative then the behavior is exactly the same as calling
2716** sqlite3_free(X).
2717** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
2718** of at least N bytes in size or NULL if insufficient memory is available.
2719** ^If M is the size of the prior allocation, then min(N,M) bytes
2720** of the prior allocation are copied into the beginning of buffer returned
2721** by sqlite3_realloc(X,N) and the prior allocation is freed.
2722** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
2723** prior allocation is not freed.
2725** ^The sqlite3_realloc64(X,N) interfaces works the same as
2726** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
2727** of a 32-bit signed integer.
2729** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
2730** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
2731** sqlite3_msize(X) returns the size of that memory allocation in bytes.
2732** ^The value returned by sqlite3_msize(X) might be larger than the number
2733** of bytes requested when X was allocated. ^If X is a NULL pointer then
2734** sqlite3_msize(X) returns zero. If X points to something that is not
2735** the beginning of memory allocation, or if it points to a formerly
2736** valid memory allocation that has now been freed, then the behavior
2737** of sqlite3_msize(X) is undefined and possibly harmful.
2739** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
2740** sqlite3_malloc64(), and sqlite3_realloc64()
2741** is always aligned to at least an 8 byte boundary, or to a
2742** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
2743** option is used.
2745** In SQLite version 3.5.0 and 3.5.1, it was possible to define
2746** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
2747** implementation of these routines to be omitted. That capability
2748** is no longer provided. Only built-in memory allocators can be used.
2750** Prior to SQLite version 3.7.10, the Windows OS interface layer called
2751** the system malloc() and free() directly when converting
2752** filenames between the UTF-8 encoding used by SQLite
2753** and whatever filename encoding is used by the particular Windows
2754** installation. Memory allocation errors were detected, but
2755** they were reported back as [SQLITE_CANTOPEN] or
2756** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
2758** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
2759** must be either NULL or else pointers obtained from a prior
2760** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
2761** not yet been released.
2763** The application must not read or write any part of
2764** a block of memory after it has been released using
2765** [sqlite3_free()] or [sqlite3_realloc()].
2767SQLITE_API void *sqlite3_malloc(int);
2768SQLITE_API void *sqlite3_malloc64(sqlite3_uint64);
2769SQLITE_API void *sqlite3_realloc(void*, int);
2770SQLITE_API void *sqlite3_realloc64(void*, sqlite3_uint64);
2771SQLITE_API void sqlite3_free(void*);
2772SQLITE_API sqlite3_uint64 sqlite3_msize(void*);
2775** CAPI3REF: Memory Allocator Statistics
2777** SQLite provides these two interfaces for reporting on the status
2778** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
2779** routines, which form the built-in memory allocation subsystem.
2781** ^The [sqlite3_memory_used()] routine returns the number of bytes
2782** of memory currently outstanding (malloced but not freed).
2783** ^The [sqlite3_memory_highwater()] routine returns the maximum
2784** value of [sqlite3_memory_used()] since the high-water mark
2785** was last reset. ^The values returned by [sqlite3_memory_used()] and
2786** [sqlite3_memory_highwater()] include any overhead
2787** added by SQLite in its implementation of [sqlite3_malloc()],
2788** but not overhead added by the any underlying system library
2789** routines that [sqlite3_malloc()] may call.
2791** ^The memory high-water mark is reset to the current value of
2792** [sqlite3_memory_used()] if and only if the parameter to
2793** [sqlite3_memory_highwater()] is true. ^The value returned
2794** by [sqlite3_memory_highwater(1)] is the high-water mark
2795** prior to the reset.
2797SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
2798SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
2801** CAPI3REF: Pseudo-Random Number Generator
2803** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
2804** select random [ROWID | ROWIDs] when inserting new records into a table that
2805** already uses the largest possible [ROWID]. The PRNG is also used for
2806** the build-in random() and randomblob() SQL functions. This interface allows
2807** applications to access the same PRNG for other purposes.
2809** ^A call to this routine stores N bytes of randomness into buffer P.
2810** ^The P parameter can be a NULL pointer.
2812** ^If this routine has not been previously called or if the previous
2813** call had N less than one or a NULL pointer for P, then the PRNG is
2814** seeded using randomness obtained from the xRandomness method of
2815** the default [sqlite3_vfs] object.
2816** ^If the previous call to this routine had an N of 1 or more and a
2817** non-NULL P then the pseudo-randomness is generated
2818** internally and without recourse to the [sqlite3_vfs] xRandomness
2819** method.
2821SQLITE_API void sqlite3_randomness(int N, void *P);
2824** CAPI3REF: Compile-Time Authorization Callbacks
2825** METHOD: sqlite3
2826** KEYWORDS: {authorizer callback}
2828** ^This routine registers an authorizer callback with a particular
2829** [database connection], supplied in the first argument.
2830** ^The authorizer callback is invoked as SQL statements are being compiled
2831** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
2832** [sqlite3_prepare_v3()], [sqlite3_prepare16()], [sqlite3_prepare16_v2()],
2833** and [sqlite3_prepare16_v3()]. ^At various
2834** points during the compilation process, as logic is being created
2835** to perform various actions, the authorizer callback is invoked to
2836** see if those actions are allowed. ^The authorizer callback should
2837** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
2838** specific action but allow the SQL statement to continue to be
2839** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
2840** rejected with an error. ^If the authorizer callback returns
2841** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
2842** then the [sqlite3_prepare_v2()] or equivalent call that triggered
2843** the authorizer will fail with an error message.
2845** When the callback returns [SQLITE_OK], that means the operation
2846** requested is ok. ^When the callback returns [SQLITE_DENY], the
2847** [sqlite3_prepare_v2()] or equivalent call that triggered the
2848** authorizer will fail with an error message explaining that
2849** access is denied.
2851** ^The first parameter to the authorizer callback is a copy of the third
2852** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
2853** to the callback is an integer [SQLITE_COPY | action code] that specifies
2854** the particular action to be authorized. ^The third through sixth parameters
2855** to the callback are either NULL pointers or zero-terminated strings
2856** that contain additional details about the action to be authorized.
2857** Applications must always be prepared to encounter a NULL pointer in any
2858** of the third through the sixth parameters of the authorization callback.
2860** ^If the action code is [SQLITE_READ]
2861** and the callback returns [SQLITE_IGNORE] then the
2862** [prepared statement] statement is constructed to substitute
2863** a NULL value in place of the table column that would have
2864** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE]
2865** return can be used to deny an untrusted user access to individual
2866** columns of a table.
2867** ^When a table is referenced by a [SELECT] but no column values are
2868** extracted from that table (for example in a query like
2869** "SELECT count(*) FROM tab") then the [SQLITE_READ] authorizer callback
2870** is invoked once for that table with a column name that is an empty string.
2871** ^If the action code is [SQLITE_DELETE] and the callback returns
2872** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
2873** [truncate optimization] is disabled and all rows are deleted individually.
2875** An authorizer is used when [sqlite3_prepare | preparing]
2876** SQL statements from an untrusted source, to ensure that the SQL statements
2877** do not try to access data they are not allowed to see, or that they do not
2878** try to execute malicious statements that damage the database. For
2879** example, an application may allow a user to enter arbitrary
2880** SQL queries for evaluation by a database. But the application does
2881** not want the user to be able to make arbitrary changes to the
2882** database. An authorizer could then be put in place while the
2883** user-entered SQL is being [sqlite3_prepare | prepared] that
2884** disallows everything except [SELECT] statements.
2886** Applications that need to process SQL from untrusted sources
2887** might also consider lowering resource limits using [sqlite3_limit()]
2888** and limiting database size using the [max_page_count] [PRAGMA]
2889** in addition to using an authorizer.
2891** ^(Only a single authorizer can be in place on a database connection
2892** at a time. Each call to sqlite3_set_authorizer overrides the
2893** previous call.)^ ^Disable the authorizer by installing a NULL callback.
2894** The authorizer is disabled by default.
2896** The authorizer callback must not do anything that will modify
2897** the database connection that invoked the authorizer callback.
2898** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2899** database connections for the meaning of "modify" in this paragraph.
2901** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
2902** statement might be re-prepared during [sqlite3_step()] due to a
2903** schema change. Hence, the application should ensure that the
2904** correct authorizer callback remains in place during the [sqlite3_step()].
2906** ^Note that the authorizer callback is invoked only during
2907** [sqlite3_prepare()] or its variants. Authorization is not
2908** performed during statement evaluation in [sqlite3_step()], unless
2909** as stated in the previous paragraph, sqlite3_step() invokes
2910** sqlite3_prepare_v2() to reprepare a statement after a schema change.
2912SQLITE_API int sqlite3_set_authorizer(
2913 sqlite3*,
2914 int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
2915 void *pUserData
2919** CAPI3REF: Authorizer Return Codes
2921** The [sqlite3_set_authorizer | authorizer callback function] must
2922** return either [SQLITE_OK] or one of these two constants in order
2923** to signal SQLite whether or not the action is permitted. See the
2924** [sqlite3_set_authorizer | authorizer documentation] for additional
2925** information.
2927** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
2928** returned from the [sqlite3_vtab_on_conflict()] interface.
2930#define SQLITE_DENY 1 /* Abort the SQL statement with an error */
2931#define SQLITE_IGNORE 2 /* Don't allow access, but don't generate an error */
2934** CAPI3REF: Authorizer Action Codes
2936** The [sqlite3_set_authorizer()] interface registers a callback function
2937** that is invoked to authorize certain SQL statement actions. The
2938** second parameter to the callback is an integer code that specifies
2939** what action is being authorized. These are the integer action codes that
2940** the authorizer callback may be passed.
2942** These action code values signify what kind of operation is to be
2943** authorized. The 3rd and 4th parameters to the authorization
2944** callback function will be parameters or NULL depending on which of these
2945** codes is used as the second parameter. ^(The 5th parameter to the
2946** authorizer callback is the name of the database ("main", "temp",
2947** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback
2948** is the name of the inner-most trigger or view that is responsible for
2949** the access attempt or NULL if this access attempt is directly from
2950** top-level SQL code.
2952/******************************************* 3rd ************ 4th ***********/
2953#define SQLITE_CREATE_INDEX 1 /* Index Name Table Name */
2954#define SQLITE_CREATE_TABLE 2 /* Table Name NULL */
2955#define SQLITE_CREATE_TEMP_INDEX 3 /* Index Name Table Name */
2956#define SQLITE_CREATE_TEMP_TABLE 4 /* Table Name NULL */
2957#define SQLITE_CREATE_TEMP_TRIGGER 5 /* Trigger Name Table Name */
2958#define SQLITE_CREATE_TEMP_VIEW 6 /* View Name NULL */
2959#define SQLITE_CREATE_TRIGGER 7 /* Trigger Name Table Name */
2960#define SQLITE_CREATE_VIEW 8 /* View Name NULL */
2961#define SQLITE_DELETE 9 /* Table Name NULL */
2962#define SQLITE_DROP_INDEX 10 /* Index Name Table Name */
2963#define SQLITE_DROP_TABLE 11 /* Table Name NULL */
2964#define SQLITE_DROP_TEMP_INDEX 12 /* Index Name Table Name */
2965#define SQLITE_DROP_TEMP_TABLE 13 /* Table Name NULL */
2966#define SQLITE_DROP_TEMP_TRIGGER 14 /* Trigger Name Table Name */
2967#define SQLITE_DROP_TEMP_VIEW 15 /* View Name NULL */
2968#define SQLITE_DROP_TRIGGER 16 /* Trigger Name Table Name */
2969#define SQLITE_DROP_VIEW 17 /* View Name NULL */
2970#define SQLITE_INSERT 18 /* Table Name NULL */
2971#define SQLITE_PRAGMA 19 /* Pragma Name 1st arg or NULL */
2972#define SQLITE_READ 20 /* Table Name Column Name */
2973#define SQLITE_SELECT 21 /* NULL NULL */
2974#define SQLITE_TRANSACTION 22 /* Operation NULL */
2975#define SQLITE_UPDATE 23 /* Table Name Column Name */
2976#define SQLITE_ATTACH 24 /* Filename NULL */
2977#define SQLITE_DETACH 25 /* Database Name NULL */
2978#define SQLITE_ALTER_TABLE 26 /* Database Name Table Name */
2979#define SQLITE_REINDEX 27 /* Index Name NULL */
2980#define SQLITE_ANALYZE 28 /* Table Name NULL */
2981#define SQLITE_CREATE_VTABLE 29 /* Table Name Module Name */
2982#define SQLITE_DROP_VTABLE 30 /* Table Name Module Name */
2983#define SQLITE_FUNCTION 31 /* NULL Function Name */
2984#define SQLITE_SAVEPOINT 32 /* Operation Savepoint Name */
2985#define SQLITE_COPY 0 /* No longer used */
2986#define SQLITE_RECURSIVE 33 /* NULL NULL */
2989** CAPI3REF: Tracing And Profiling Functions
2990** METHOD: sqlite3
2992** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
2993** instead of the routines described here.
2995** These routines register callback functions that can be used for
2996** tracing and profiling the execution of SQL statements.
2998** ^The callback function registered by sqlite3_trace() is invoked at
2999** various times when an SQL statement is being run by [sqlite3_step()].
3000** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
3001** SQL statement text as the statement first begins executing.
3002** ^(Additional sqlite3_trace() callbacks might occur
3003** as each triggered subprogram is entered. The callbacks for triggers
3004** contain a UTF-8 SQL comment that identifies the trigger.)^
3006** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
3007** the length of [bound parameter] expansion in the output of sqlite3_trace().
3009** ^The callback function registered by sqlite3_profile() is invoked
3010** as each SQL statement finishes. ^The profile callback contains
3011** the original statement text and an estimate of wall-clock time
3012** of how long that statement took to run. ^The profile callback
3013** time is in units of nanoseconds, however the current implementation
3014** is only capable of millisecond resolution so the six least significant
3015** digits in the time are meaningless. Future versions of SQLite
3016** might provide greater resolution on the profiler callback. Invoking
3017** either [sqlite3_trace()] or [sqlite3_trace_v2()] will cancel the
3018** profile callback.
3020SQLITE_API SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
3021 void(*xTrace)(void*,const char*), void*);
3022SQLITE_API SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
3023 void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
3026** CAPI3REF: SQL Trace Event Codes
3029** These constants identify classes of events that can be monitored
3030** using the [sqlite3_trace_v2()] tracing logic. The M argument
3031** to [sqlite3_trace_v2(D,M,X,P)] is an OR-ed combination of one or more of
3032** the following constants. ^The first argument to the trace callback
3033** is one of the following constants.
3035** New tracing constants may be added in future releases.
3037** ^A trace callback has four arguments: xCallback(T,C,P,X).
3038** ^The T argument is one of the integer type codes above.
3039** ^The C argument is a copy of the context pointer passed in as the
3040** fourth argument to [sqlite3_trace_v2()].
3041** The P and X arguments are pointers whose meanings depend on T.
3043** <dl>
3045** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
3046** first begins running and possibly at other times during the
3047** execution of the prepared statement, such as at the start of each
3048** trigger subprogram. ^The P argument is a pointer to the
3049** [prepared statement]. ^The X argument is a pointer to a string which
3050** is the unexpanded SQL text of the prepared statement or an SQL comment
3051** that indicates the invocation of a trigger. ^The callback can compute
3052** the same text that would have been returned by the legacy [sqlite3_trace()]
3053** interface by using the X argument when X begins with "--" and invoking
3054** [sqlite3_expanded_sql(P)] otherwise.
3057** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
3058** information as is provided by the [sqlite3_profile()] callback.
3059** ^The P argument is a pointer to the [prepared statement] and the
3060** X argument points to a 64-bit integer which is the estimated of
3061** the number of nanosecond that the prepared statement took to run.
3062** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
3065** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
3066** statement generates a single row of result.
3067** ^The P argument is a pointer to the [prepared statement] and the
3068** X argument is unused.
3071** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
3072** connection closes.
3073** ^The P argument is a pointer to the [database connection] object
3074** and the X argument is unused.
3075** </dl>
3077#define SQLITE_TRACE_STMT 0x01
3078#define SQLITE_TRACE_PROFILE 0x02
3079#define SQLITE_TRACE_ROW 0x04
3080#define SQLITE_TRACE_CLOSE 0x08
3083** CAPI3REF: SQL Trace Hook
3084** METHOD: sqlite3
3086** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
3087** function X against [database connection] D, using property mask M
3088** and context pointer P. ^If the X callback is
3089** NULL or if the M mask is zero, then tracing is disabled. The
3090** M argument should be the bitwise OR-ed combination of
3091** zero or more [SQLITE_TRACE] constants.
3093** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides
3094** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
3096** ^The X callback is invoked whenever any of the events identified by
3097** mask M occur. ^The integer return value from the callback is currently
3098** ignored, though this may change in future releases. Callback
3099** implementations should return zero to ensure future compatibility.
3101** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
3102** ^The T argument is one of the [SQLITE_TRACE]
3103** constants to indicate why the callback was invoked.
3104** ^The C argument is a copy of the context pointer.
3105** The P and X arguments are pointers whose meanings depend on T.
3107** The sqlite3_trace_v2() interface is intended to replace the legacy
3108** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
3109** are deprecated.
3111SQLITE_API int sqlite3_trace_v2(
3112 sqlite3*,
3113 unsigned uMask,
3114 int(*xCallback)(unsigned,void*,void*,void*),
3115 void *pCtx
3119** CAPI3REF: Query Progress Callbacks
3120** METHOD: sqlite3
3122** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
3123** function X to be invoked periodically during long running calls to
3124** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
3125** database connection D. An example use for this
3126** interface is to keep a GUI updated during a large query.
3128** ^The parameter P is passed through as the only parameter to the
3129** callback function X. ^The parameter N is the approximate number of
3130** [virtual machine instructions] that are evaluated between successive
3131** invocations of the callback X. ^If N is less than one then the progress
3132** handler is disabled.
3134** ^Only a single progress handler may be defined at one time per
3135** [database connection]; setting a new progress handler cancels the
3136** old one. ^Setting parameter X to NULL disables the progress handler.
3137** ^The progress handler is also disabled by setting N to a value less
3138** than 1.
3140** ^If the progress callback returns non-zero, the operation is
3141** interrupted. This feature can be used to implement a
3142** "Cancel" button on a GUI progress dialog box.
3144** The progress handler callback must not do anything that will modify
3145** the database connection that invoked the progress handler.
3146** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
3147** database connections for the meaning of "modify" in this paragraph.
3150SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
3153** CAPI3REF: Opening A New Database Connection
3154** CONSTRUCTOR: sqlite3
3156** ^These routines open an SQLite database file as specified by the
3157** filename argument. ^The filename argument is interpreted as UTF-8 for
3158** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
3159** order for sqlite3_open16(). ^(A [database connection] handle is usually
3160** returned in *ppDb, even if an error occurs. The only exception is that
3161** if SQLite is unable to allocate memory to hold the [sqlite3] object,
3162** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
3163** object.)^ ^(If the database is opened (and/or created) successfully, then
3164** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The
3165** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
3166** an English language description of the error following a failure of any
3167** of the sqlite3_open() routines.
3169** ^The default encoding will be UTF-8 for databases created using
3170** sqlite3_open() or sqlite3_open_v2(). ^The default encoding for databases
3171** created using sqlite3_open16() will be UTF-16 in the native byte order.
3173** Whether or not an error occurs when it is opened, resources
3174** associated with the [database connection] handle should be released by
3175** passing it to [sqlite3_close()] when it is no longer required.
3177** The sqlite3_open_v2() interface works like sqlite3_open()
3178** except that it accepts two additional parameters for additional control
3179** over the new database connection. ^(The flags parameter to
3180** sqlite3_open_v2() can take one of
3181** the following three values, optionally combined with the
3185** <dl>
3186** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
3187** <dd>The database is opened in read-only mode. If the database does not
3188** already exist, an error is returned.</dd>)^
3190** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
3191** <dd>The database is opened for reading and writing if possible, or reading
3192** only if the file is write protected by the operating system. In either
3193** case the database must already exist, otherwise an error is returned.</dd>)^
3196** <dd>The database is opened for reading and writing, and is created if
3197** it does not already exist. This is the behavior that is always used for
3198** sqlite3_open() and sqlite3_open16().</dd>)^
3199** </dl>
3201** If the 3rd parameter to sqlite3_open_v2() is not one of the
3202** combinations shown above optionally combined with other
3204** then the behavior is undefined.
3206** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
3207** opens in the multi-thread [threading mode] as long as the single-thread
3208** mode has not been set at compile-time or start-time. ^If the
3209** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
3210** in the serialized [threading mode] unless single-thread was
3211** previously selected at compile-time or start-time.
3212** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
3213** eligible to use [shared cache mode], regardless of whether or not shared
3214** cache is enabled using [sqlite3_enable_shared_cache()]. ^The
3215** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
3216** participate in [shared cache mode] even if it is enabled.
3218** ^The fourth parameter to sqlite3_open_v2() is the name of the
3219** [sqlite3_vfs] object that defines the operating system interface that
3220** the new database connection should use. ^If the fourth parameter is
3221** a NULL pointer then the default [sqlite3_vfs] object is used.
3223** ^If the filename is ":memory:", then a private, temporary in-memory database
3224** is created for the connection. ^This in-memory database will vanish when
3225** the database connection is closed. Future versions of SQLite might
3226** make use of additional special filenames that begin with the ":" character.
3227** It is recommended that when a database filename actually does begin with
3228** a ":" character you should prefix the filename with a pathname such as
3229** "./" to avoid ambiguity.
3231** ^If the filename is an empty string, then a private, temporary
3232** on-disk database will be created. ^This private database will be
3233** automatically deleted as soon as the database connection is closed.
3235** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
3237** ^If [URI filename] interpretation is enabled, and the filename argument
3238** begins with "file:", then the filename is interpreted as a URI. ^URI
3239** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
3240** set in the third argument to sqlite3_open_v2(), or if it has
3241** been enabled globally using the [SQLITE_CONFIG_URI] option with the
3242** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
3243** URI filename interpretation is turned off
3244** by default, but future releases of SQLite might enable URI filename
3245** interpretation by default. See "[URI filenames]" for additional
3246** information.
3248** URI filenames are parsed according to RFC 3986. ^If the URI contains an
3249** authority, then it must be either an empty string or the string
3250** "localhost". ^If the authority is not an empty string or "localhost", an
3251** error is returned to the caller. ^The fragment component of a URI, if
3252** present, is ignored.
3254** ^SQLite uses the path component of the URI as the name of the disk file
3255** which contains the database. ^If the path begins with a '/' character,
3256** then it is interpreted as an absolute path. ^If the path does not begin
3257** with a '/' (meaning that the authority section is omitted from the URI)
3258** then the path is interpreted as a relative path.
3259** ^(On windows, the first component of an absolute path
3260** is a drive specification (e.g. "C:").)^
3262** [[core URI query parameters]]
3263** The query component of a URI may contain parameters that are interpreted
3264** either by SQLite itself, or by a [VFS | custom VFS implementation].
3265** SQLite and its built-in [VFSes] interpret the
3266** following query parameters:
3268** <ul>
3269** <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
3270** a VFS object that provides the operating system interface that should
3271** be used to access the database file on disk. ^If this option is set to
3272** an empty string the default VFS object is used. ^Specifying an unknown
3273** VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
3274** present, then the VFS specified by the option takes precedence over
3275** the value passed as the fourth parameter to sqlite3_open_v2().
3277** <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
3278** "rwc", or "memory". Attempting to set it to any other value is
3279** an error)^.
3280** ^If "ro" is specified, then the database is opened for read-only
3281** access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the
3282** third argument to sqlite3_open_v2(). ^If the mode option is set to
3283** "rw", then the database is opened for read-write (but not create)
3284** access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had
3285** been set. ^Value "rwc" is equivalent to setting both
3286** SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE. ^If the mode option is
3287** set to "memory" then a pure [in-memory database] that never reads
3288** or writes from disk is used. ^It is an error to specify a value for
3289** the mode parameter that is less restrictive than that specified by
3290** the flags passed in the third parameter to sqlite3_open_v2().
3292** <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
3293** "private". ^Setting it to "shared" is equivalent to setting the
3294** SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
3295** sqlite3_open_v2(). ^Setting the cache parameter to "private" is
3296** equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
3297** ^If sqlite3_open_v2() is used and the "cache" parameter is present in
3298** a URI filename, its value overrides any behavior requested by setting
3301** <li> <b>psow</b>: ^The psow parameter indicates whether or not the
3302** [powersafe overwrite] property does or does not apply to the
3303** storage media on which the database file resides.
3305** <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
3306** which if set disables file locking in rollback journal modes. This
3307** is useful for accessing a database on a filesystem that does not
3308** support locking. Caution: Database corruption might result if two
3309** or more processes write to the same database and any one of those
3310** processes uses nolock=1.
3312** <li> <b>immutable</b>: ^The immutable parameter is a boolean query
3313** parameter that indicates that the database file is stored on
3314** read-only media. ^When immutable is set, SQLite assumes that the
3315** database file cannot be changed, even by a process with higher
3316** privilege, and so the database is opened read-only and all locking
3317** and change detection is disabled. Caution: Setting the immutable
3318** property on a database file that does in fact change can result
3319** in incorrect query results and/or [SQLITE_CORRUPT] errors.
3320** See also: [SQLITE_IOCAP_IMMUTABLE].
3322** </ul>
3324** ^Specifying an unknown parameter in the query component of a URI is not an
3325** error. Future versions of SQLite might understand additional query
3326** parameters. See "[query parameters with special meaning to SQLite]" for
3327** additional information.
3329** [[URI filename examples]] <h3>URI filename examples</h3>
3331** <table border="1" align=center cellpadding=5>
3332** <tr><th> URI filenames <th> Results
3333** <tr><td> file:data.db <td>
3334** Open the file "data.db" in the current directory.
3335** <tr><td> file:/home/fred/data.db<br>
3336** file:///home/fred/data.db <br>
3337** file://localhost/home/fred/data.db <br> <td>
3338** Open the database file "/home/fred/data.db".
3339** <tr><td> file://darkstar/home/fred/data.db <td>
3340** An error. "darkstar" is not a recognized authority.
3341** <tr><td style="white-space:nowrap">
3342** file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
3343** <td> Windows only: Open the file "data.db" on fred's desktop on drive
3344** C:. Note that the %20 escaping in this example is not strictly
3345** necessary - space characters can be used literally
3346** in URI filenames.
3347** <tr><td> file:data.db?mode=ro&cache=private <td>
3348** Open file "data.db" in the current directory for read-only access.
3349** Regardless of whether or not shared-cache mode is enabled by
3350** default, use a private cache.
3351** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
3352** Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
3353** that uses dot-files in place of posix advisory locking.
3354** <tr><td> file:data.db?mode=readonly <td>
3355** An error. "readonly" is not a valid option for the "mode" parameter.
3356** </table>
3358** ^URI hexadecimal escape sequences (%HH) are supported within the path and
3359** query components of a URI. A hexadecimal escape sequence consists of a
3360** percent sign - "%" - followed by exactly two hexadecimal digits
3361** specifying an octet value. ^Before the path or query components of a
3362** URI filename are interpreted, they are encoded using UTF-8 and all
3363** hexadecimal escape sequences replaced by a single byte containing the
3364** corresponding octet. If this process generates an invalid UTF-8 encoding,
3365** the results are undefined.
3367** <b>Note to Windows users:</b> The encoding used for the filename argument
3368** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
3369** codepage is currently defined. Filenames containing international
3370** characters must be converted to UTF-8 prior to passing them into
3371** sqlite3_open() or sqlite3_open_v2().
3373** <b>Note to Windows Runtime users:</b> The temporary directory must be set
3374** prior to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various
3375** features that require the use of temporary files may fail.
3377** See also: [sqlite3_temp_directory]
3379SQLITE_API int sqlite3_open(
3380 const char *filename, /* Database filename (UTF-8) */
3381 sqlite3 **ppDb /* OUT: SQLite db handle */
3383SQLITE_API int sqlite3_open16(
3384 const void *filename, /* Database filename (UTF-16) */
3385 sqlite3 **ppDb /* OUT: SQLite db handle */
3387SQLITE_API int sqlite3_open_v2(
3388 const char *filename, /* Database filename (UTF-8) */
3389 sqlite3 **ppDb, /* OUT: SQLite db handle */
3390 int flags, /* Flags */
3391 const char *zVfs /* Name of VFS module to use */
3395** CAPI3REF: Obtain Values For URI Parameters
3397** These are utility routines, useful to VFS implementations, that check
3398** to see if a database file was a URI that contained a specific query
3399** parameter, and if so obtains the value of that query parameter.
3401** If F is the database filename pointer passed into the xOpen() method of
3402** a VFS implementation when the flags parameter to xOpen() has one or
3403** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
3404** P is the name of the query parameter, then
3405** sqlite3_uri_parameter(F,P) returns the value of the P
3406** parameter if it exists or a NULL pointer if P does not appear as a
3407** query parameter on F. If P is a query parameter of F
3408** has no explicit value, then sqlite3_uri_parameter(F,P) returns
3409** a pointer to an empty string.
3411** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
3412** parameter and returns true (1) or false (0) according to the value
3413** of P. The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
3414** value of query parameter P is one of "yes", "true", or "on" in any
3415** case or if the value begins with a non-zero number. The
3416** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
3417** query parameter P is one of "no", "false", or "off" in any case or
3418** if the value begins with a numeric zero. If P is not a query
3419** parameter on F or if the value of P is does not match any of the
3420** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
3422** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
3423** 64-bit signed integer and returns that integer, or D if P does not
3424** exist. If the value of P is something other than an integer, then
3425** zero is returned.
3427** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
3428** sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and
3429** is not a database file pathname pointer that SQLite passed into the xOpen
3430** VFS method, then the behavior of this routine is undefined and probably
3431** undesirable.
3433** See the [URI filename] documentation for additional information.
3435SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
3436SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
3437SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
3441** CAPI3REF: Error Codes And Messages
3442** METHOD: sqlite3
3444** ^If the most recent sqlite3_* API call associated with
3445** [database connection] D failed, then the sqlite3_errcode(D) interface
3446** returns the numeric [result code] or [extended result code] for that
3447** API call.
3448** ^The sqlite3_extended_errcode()
3449** interface is the same except that it always returns the
3450** [extended result code] even when extended result codes are
3451** disabled.
3453** The values returned by sqlite3_errcode() and/or
3454** sqlite3_extended_errcode() might change with each API call.
3455** Except, there are some interfaces that are guaranteed to never
3456** change the value of the error code. The error-code preserving
3457** interfaces are:
3459** <ul>
3460** <li> sqlite3_errcode()
3461** <li> sqlite3_extended_errcode()
3462** <li> sqlite3_errmsg()
3463** <li> sqlite3_errmsg16()
3464** </ul>
3466** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
3467** text that describes the error, as either UTF-8 or UTF-16 respectively.
3468** ^(Memory to hold the error message string is managed internally.
3469** The application does not need to worry about freeing the result.
3470** However, the error string might be overwritten or deallocated by
3471** subsequent calls to other SQLite interface functions.)^
3473** ^The sqlite3_errstr() interface returns the English-language text
3474** that describes the [result code], as UTF-8.
3475** ^(Memory to hold the error message string is managed internally
3476** and must not be freed by the application)^.
3478** When the serialized [threading mode] is in use, it might be the
3479** case that a second error occurs on a separate thread in between
3480** the time of the first error and the call to these interfaces.
3481** When that happens, the second error will be reported since these
3482** interfaces always report the most recent result. To avoid
3483** this, each thread can obtain exclusive use of the [database connection] D
3484** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
3485** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
3486** all calls to the interfaces listed here are completed.
3488** If an interface fails with SQLITE_MISUSE, that means the interface
3489** was invoked incorrectly by the application. In that case, the
3490** error code and message may or may not be set.
3492SQLITE_API int sqlite3_errcode(sqlite3 *db);
3493SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
3494SQLITE_API const char *sqlite3_errmsg(sqlite3*);
3495SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
3496SQLITE_API const char *sqlite3_errstr(int);
3499** CAPI3REF: Prepared Statement Object
3500** KEYWORDS: {prepared statement} {prepared statements}
3502** An instance of this object represents a single SQL statement that
3503** has been compiled into binary form and is ready to be evaluated.
3505** Think of each SQL statement as a separate computer program. The
3506** original SQL text is source code. A prepared statement object
3507** is the compiled object code. All SQL must be converted into a
3508** prepared statement before it can be run.
3510** The life-cycle of a prepared statement object usually goes like this:
3512** <ol>
3513** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
3514** <li> Bind values to [parameters] using the sqlite3_bind_*()
3515** interfaces.
3516** <li> Run the SQL by calling [sqlite3_step()] one or more times.
3517** <li> Reset the prepared statement using [sqlite3_reset()] then go back
3518** to step 2. Do this zero or more times.
3519** <li> Destroy the object using [sqlite3_finalize()].
3520** </ol>
3522typedef struct sqlite3_stmt sqlite3_stmt;
3525** CAPI3REF: Run-time Limits
3526** METHOD: sqlite3
3528** ^(This interface allows the size of various constructs to be limited
3529** on a connection by connection basis. The first parameter is the
3530** [database connection] whose limit is to be set or queried. The
3531** second parameter is one of the [limit categories] that define a
3532** class of constructs to be size limited. The third parameter is the
3533** new limit for that construct.)^
3535** ^If the new limit is a negative number, the limit is unchanged.
3536** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a
3537** [limits | hard upper bound]
3538** set at compile-time by a C preprocessor macro called
3539** [limits | SQLITE_MAX_<i>NAME</i>].
3540** (The "_LIMIT_" in the name is changed to "_MAX_".))^
3541** ^Attempts to increase a limit above its hard upper bound are
3542** silently truncated to the hard upper bound.
3544** ^Regardless of whether or not the limit was changed, the
3545** [sqlite3_limit()] interface returns the prior value of the limit.
3546** ^Hence, to find the current value of a limit without changing it,
3547** simply invoke this interface with the third parameter set to -1.
3549** Run-time limits are intended for use in applications that manage
3550** both their own internal database and also databases that are controlled
3551** by untrusted external sources. An example application might be a
3552** web browser that has its own databases for storing history and
3553** separate databases controlled by JavaScript applications downloaded
3554** off the Internet. The internal databases can be given the
3555** large, default limits. Databases managed by external sources can
3556** be given much smaller limits designed to prevent a denial of service
3557** attack. Developers might also want to use the [sqlite3_set_authorizer()]
3558** interface to further control untrusted SQL. The size of the database
3559** created by an untrusted script can be contained using the
3560** [max_page_count] [PRAGMA].
3562** New run-time limit categories may be added in future releases.
3564SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
3567** CAPI3REF: Run-Time Limit Categories
3568** KEYWORDS: {limit category} {*limit categories}
3570** These constants define various performance limits
3571** that can be lowered at run-time using [sqlite3_limit()].
3572** The synopsis of the meanings of the various limits is shown below.
3573** Additional information is available at [limits | Limits in SQLite].
3575** <dl>
3577** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
3580** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
3583** <dd>The maximum number of columns in a table definition or in the
3584** result set of a [SELECT] or the maximum number of columns in an index
3585** or in an ORDER BY or GROUP BY clause.</dd>)^
3588** <dd>The maximum depth of the parse tree on any expression.</dd>)^
3591** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
3594** <dd>The maximum number of instructions in a virtual machine program
3595** used to implement an SQL statement. If [sqlite3_prepare_v2()] or
3596** the equivalent tries to allocate space for more than this many opcodes
3597** in a single prepared statement, an SQLITE_NOMEM error is returned.</dd>)^
3600** <dd>The maximum number of arguments on a function.</dd>)^
3603** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
3607** <dd>The maximum length of the pattern argument to the [LIKE] or
3608** [GLOB] operators.</dd>)^
3612** <dd>The maximum index number of any [parameter] in an SQL statement.)^
3615** <dd>The maximum depth of recursion for triggers.</dd>)^
3618** <dd>The maximum number of auxiliary worker threads that a single
3619** [prepared statement] may start.</dd>)^
3620** </dl>
3627#define SQLITE_LIMIT_VDBE_OP 5
3636** CAPI3REF: Prepare Flags
3638** These constants define various flags that can be passed into
3639** "prepFlags" parameter of the [sqlite3_prepare_v3()] and
3640** [sqlite3_prepare16_v3()] interfaces.
3642** New flags may be added in future releases of SQLite.
3644** <dl>
3646** <dd>The SQLITE_PREPARE_PERSISTENT flag is a hint to the query planner
3647** that the prepared statement will be retained for a long time and
3648** probably reused many times.)^ ^Without this flag, [sqlite3_prepare_v3()]
3649** and [sqlite3_prepare16_v3()] assume that the prepared statement will
3650** be used just once or at most a few times and then destroyed using
3651** [sqlite3_finalize()] relatively soon. The current implementation acts
3652** on this hint by avoiding the use of [lookaside memory] so as not to
3653** deplete the limited store of lookaside memory. Future versions of
3654** SQLite may act on this hint differently.
3657** <dd>The SQLITE_PREPARE_NORMALIZE flag is a no-op. This flag used
3658** to be required for any prepared statement that wanted to use the
3659** [sqlite3_normalized_sql()] interface. However, the
3660** [sqlite3_normalized_sql()] interface is now available to all
3661** prepared statements, regardless of whether or not they use this
3662** flag.
3665** <dd>The SQLITE_PREPARE_NO_VTAB flag causes the SQL compiler
3666** to return an error (error code SQLITE_ERROR) if the statement uses
3667** any virtual tables.
3668** </dl>
3672#define SQLITE_PREPARE_NO_VTAB 0x04
3675** CAPI3REF: Compiling An SQL Statement
3676** KEYWORDS: {SQL statement compiler}
3677** METHOD: sqlite3
3678** CONSTRUCTOR: sqlite3_stmt
3680** To execute an SQL statement, it must first be compiled into a byte-code
3681** program using one of these routines. Or, in other words, these routines
3682** are constructors for the [prepared statement] object.
3684** The preferred routine to use is [sqlite3_prepare_v2()]. The
3685** [sqlite3_prepare()] interface is legacy and should be avoided.
3686** [sqlite3_prepare_v3()] has an extra "prepFlags" option that is used
3687** for special purposes.
3689** The use of the UTF-8 interfaces is preferred, as SQLite currently
3690** does all parsing using UTF-8. The UTF-16 interfaces are provided
3691** as a convenience. The UTF-16 interfaces work by converting the
3692** input text into UTF-8, then invoking the corresponding UTF-8 interface.
3694** The first argument, "db", is a [database connection] obtained from a
3695** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
3696** [sqlite3_open16()]. The database connection must not have been closed.
3698** The second argument, "zSql", is the statement to be compiled, encoded
3699** as either UTF-8 or UTF-16. The sqlite3_prepare(), sqlite3_prepare_v2(),
3700** and sqlite3_prepare_v3()
3701** interfaces use UTF-8, and sqlite3_prepare16(), sqlite3_prepare16_v2(),
3702** and sqlite3_prepare16_v3() use UTF-16.
3704** ^If the nByte argument is negative, then zSql is read up to the
3705** first zero terminator. ^If nByte is positive, then it is the
3706** number of bytes read from zSql. ^If nByte is zero, then no prepared
3707** statement is generated.
3708** If the caller knows that the supplied string is nul-terminated, then
3709** there is a small performance advantage to passing an nByte parameter that
3710** is the number of bytes in the input string <i>including</i>
3711** the nul-terminator.
3713** ^If pzTail is not NULL then *pzTail is made to point to the first byte
3714** past the end of the first SQL statement in zSql. These routines only
3715** compile the first statement in zSql, so *pzTail is left pointing to
3716** what remains uncompiled.
3718** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
3719** executed using [sqlite3_step()]. ^If there is an error, *ppStmt is set
3720** to NULL. ^If the input text contains no SQL (if the input is an empty
3721** string or a comment) then *ppStmt is set to NULL.
3722** The calling procedure is responsible for deleting the compiled
3723** SQL statement using [sqlite3_finalize()] after it has finished with it.
3724** ppStmt may not be NULL.
3726** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
3727** otherwise an [error code] is returned.
3729** The sqlite3_prepare_v2(), sqlite3_prepare_v3(), sqlite3_prepare16_v2(),
3730** and sqlite3_prepare16_v3() interfaces are recommended for all new programs.
3731** The older interfaces (sqlite3_prepare() and sqlite3_prepare16())
3732** are retained for backwards compatibility, but their use is discouraged.
3733** ^In the "vX" interfaces, the prepared statement
3734** that is returned (the [sqlite3_stmt] object) contains a copy of the
3735** original SQL text. This causes the [sqlite3_step()] interface to
3736** behave differently in three ways:
3738** <ol>
3739** <li>
3740** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
3741** always used to do, [sqlite3_step()] will automatically recompile the SQL
3742** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
3743** retries will occur before sqlite3_step() gives up and returns an error.
3744** </li>
3746** <li>
3747** ^When an error occurs, [sqlite3_step()] will return one of the detailed
3748** [error codes] or [extended error codes]. ^The legacy behavior was that
3749** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
3750** and the application would have to make a second call to [sqlite3_reset()]
3751** in order to find the underlying cause of the problem. With the "v2" prepare
3752** interfaces, the underlying reason for the error is returned immediately.
3753** </li>
3755** <li>
3756** ^If the specific value bound to [parameter | host parameter] in the
3757** WHERE clause might influence the choice of query plan for a statement,
3758** then the statement will be automatically recompiled, as if there had been
3759** a schema change, on the first [sqlite3_step()] call following any change
3760** to the [sqlite3_bind_text | bindings] of that [parameter].
3761** ^The specific value of WHERE-clause [parameter] might influence the
3762** choice of query plan if the parameter is the left-hand side of a [LIKE]
3763** or [GLOB] operator or if the parameter is compared to an indexed column
3764** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
3765** </li>
3766** </ol>
3768** <p>^sqlite3_prepare_v3() differs from sqlite3_prepare_v2() only in having
3769** the extra prepFlags parameter, which is a bit array consisting of zero or
3770** more of the [SQLITE_PREPARE_PERSISTENT|SQLITE_PREPARE_*] flags. ^The
3771** sqlite3_prepare_v2() interface works exactly the same as
3772** sqlite3_prepare_v3() with a zero prepFlags parameter.
3774SQLITE_API int sqlite3_prepare(
3775 sqlite3 *db, /* Database handle */
3776 const char *zSql, /* SQL statement, UTF-8 encoded */
3777 int nByte, /* Maximum length of zSql in bytes. */
3778 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3779 const char **pzTail /* OUT: Pointer to unused portion of zSql */
3781SQLITE_API int sqlite3_prepare_v2(
3782 sqlite3 *db, /* Database handle */
3783 const char *zSql, /* SQL statement, UTF-8 encoded */
3784 int nByte, /* Maximum length of zSql in bytes. */
3785 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3786 const char **pzTail /* OUT: Pointer to unused portion of zSql */
3788SQLITE_API int sqlite3_prepare_v3(
3789 sqlite3 *db, /* Database handle */
3790 const char *zSql, /* SQL statement, UTF-8 encoded */
3791 int nByte, /* Maximum length of zSql in bytes. */
3792 unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */
3793 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3794 const char **pzTail /* OUT: Pointer to unused portion of zSql */
3796SQLITE_API int sqlite3_prepare16(
3797 sqlite3 *db, /* Database handle */
3798 const void *zSql, /* SQL statement, UTF-16 encoded */
3799 int nByte, /* Maximum length of zSql in bytes. */
3800 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3801 const void **pzTail /* OUT: Pointer to unused portion of zSql */
3803SQLITE_API int sqlite3_prepare16_v2(
3804 sqlite3 *db, /* Database handle */
3805 const void *zSql, /* SQL statement, UTF-16 encoded */
3806 int nByte, /* Maximum length of zSql in bytes. */
3807 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3808 const void **pzTail /* OUT: Pointer to unused portion of zSql */
3810SQLITE_API int sqlite3_prepare16_v3(
3811 sqlite3 *db, /* Database handle */
3812 const void *zSql, /* SQL statement, UTF-16 encoded */
3813 int nByte, /* Maximum length of zSql in bytes. */
3814 unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */
3815 sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3816 const void **pzTail /* OUT: Pointer to unused portion of zSql */
3820** CAPI3REF: Retrieving Statement SQL
3821** METHOD: sqlite3_stmt
3823** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
3824** SQL text used to create [prepared statement] P if P was
3825** created by [sqlite3_prepare_v2()], [sqlite3_prepare_v3()],
3826** [sqlite3_prepare16_v2()], or [sqlite3_prepare16_v3()].
3827** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
3828** string containing the SQL text of prepared statement P with
3829** [bound parameters] expanded.
3830** ^The sqlite3_normalized_sql(P) interface returns a pointer to a UTF-8
3831** string containing the normalized SQL text of prepared statement P. The
3832** semantics used to normalize a SQL statement are unspecified and subject
3833** to change. At a minimum, literal values will be replaced with suitable
3834** placeholders.
3836** ^(For example, if a prepared statement is created using the SQL
3837** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
3838** and parameter :xyz is unbound, then sqlite3_sql() will return
3839** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
3840** will return "SELECT 2345,NULL".)^
3842** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
3843** is available to hold the result, or if the result would exceed the
3844** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
3846** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
3847** bound parameter expansions. ^The [SQLITE_OMIT_TRACE] compile-time
3848** option causes sqlite3_expanded_sql() to always return NULL.
3850** ^The strings returned by sqlite3_sql(P) and sqlite3_normalized_sql(P)
3851** are managed by SQLite and are automatically freed when the prepared
3852** statement is finalized.
3853** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
3854** is obtained from [sqlite3_malloc()] and must be free by the application
3855** by passing it to [sqlite3_free()].
3857SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
3858SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
3859SQLITE_API const char *sqlite3_normalized_sql(sqlite3_stmt *pStmt);
3862** CAPI3REF: Determine If An SQL Statement Writes The Database
3863** METHOD: sqlite3_stmt
3865** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
3866** and only if the [prepared statement] X makes no direct changes to
3867** the content of the database file.
3869** Note that [application-defined SQL functions] or
3870** [virtual tables] might change the database indirectly as a side effect.
3871** ^(For example, if an application defines a function "eval()" that
3872** calls [sqlite3_exec()], then the following SQL statement would
3873** change the database file through side-effects:
3875** <blockquote><pre>
3876** SELECT eval('DELETE FROM t1') FROM t2;
3877** </pre></blockquote>
3879** But because the [SELECT] statement does not change the database file
3880** directly, sqlite3_stmt_readonly() would still return true.)^
3882** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
3883** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
3884** since the statements themselves do not actually modify the database but
3885** rather they control the timing of when other statements modify the
3886** database. ^The [ATTACH] and [DETACH] statements also cause
3887** sqlite3_stmt_readonly() to return true since, while those statements
3888** change the configuration of a database connection, they do not make
3889** changes to the content of the database files on disk.
3890** ^The sqlite3_stmt_readonly() interface returns true for [BEGIN] since
3891** [BEGIN] merely sets internal flags, but the [BEGIN|BEGIN IMMEDIATE] and
3892** [BEGIN|BEGIN EXCLUSIVE] commands do touch the database and so
3893** sqlite3_stmt_readonly() returns false for those commands.
3895SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
3898** CAPI3REF: Determine If A Prepared Statement Has Been Reset
3899** METHOD: sqlite3_stmt
3901** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
3902** [prepared statement] S has been stepped at least once using
3903** [sqlite3_step(S)] but has neither run to completion (returned
3904** [SQLITE_DONE] from [sqlite3_step(S)]) nor
3905** been reset using [sqlite3_reset(S)]. ^The sqlite3_stmt_busy(S)
3906** interface returns false if S is a NULL pointer. If S is not a
3907** NULL pointer and is not a pointer to a valid [prepared statement]
3908** object, then the behavior is undefined and probably undesirable.
3910** This interface can be used in combination [sqlite3_next_stmt()]
3911** to locate all prepared statements associated with a database
3912** connection that are in need of being reset. This can be used,
3913** for example, in diagnostic routines to search for prepared
3914** statements that are holding a transaction open.
3916SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
3919** CAPI3REF: Dynamically Typed Value Object
3920** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
3922** SQLite uses the sqlite3_value object to represent all values
3923** that can be stored in a database table. SQLite uses dynamic typing
3924** for the values it stores. ^Values stored in sqlite3_value objects
3925** can be integers, floating point values, strings, BLOBs, or NULL.
3927** An sqlite3_value object may be either "protected" or "unprotected".
3928** Some interfaces require a protected sqlite3_value. Other interfaces
3929** will accept either a protected or an unprotected sqlite3_value.
3930** Every interface that accepts sqlite3_value arguments specifies
3931** whether or not it requires a protected sqlite3_value. The
3932** [sqlite3_value_dup()] interface can be used to construct a new
3933** protected sqlite3_value from an unprotected sqlite3_value.
3935** The terms "protected" and "unprotected" refer to whether or not
3936** a mutex is held. An internal mutex is held for a protected
3937** sqlite3_value object but no mutex is held for an unprotected
3938** sqlite3_value object. If SQLite is compiled to be single-threaded
3939** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
3940** or if SQLite is run in one of reduced mutex modes
3942** then there is no distinction between protected and unprotected
3943** sqlite3_value objects and they can be used interchangeably. However,
3944** for maximum code portability it is recommended that applications
3945** still make the distinction between protected and unprotected
3946** sqlite3_value objects even when not strictly required.
3948** ^The sqlite3_value objects that are passed as parameters into the
3949** implementation of [application-defined SQL functions] are protected.
3950** ^The sqlite3_value object returned by
3951** [sqlite3_column_value()] is unprotected.
3952** Unprotected sqlite3_value objects may only be used as arguments
3953** to [sqlite3_result_value()], [sqlite3_bind_value()], and
3954** [sqlite3_value_dup()].
3955** The [sqlite3_value_blob | sqlite3_value_type()] family of
3956** interfaces require protected sqlite3_value objects.
3958typedef struct sqlite3_value sqlite3_value;
3961** CAPI3REF: SQL Function Context Object
3963** The context in which an SQL function executes is stored in an
3964** sqlite3_context object. ^A pointer to an sqlite3_context object
3965** is always first parameter to [application-defined SQL functions].
3966** The application-defined SQL function implementation will pass this
3967** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
3968** [sqlite3_aggregate_context()], [sqlite3_user_data()],
3969** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
3970** and/or [sqlite3_set_auxdata()].
3972typedef struct sqlite3_context sqlite3_context;
3975** CAPI3REF: Binding Values To Prepared Statements
3976** KEYWORDS: {host parameter} {host parameters} {host parameter name}
3977** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
3978** METHOD: sqlite3_stmt
3980** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
3981** literals may be replaced by a [parameter] that matches one of following
3982** templates:
3984** <ul>
3985** <li> ?
3986** <li> ?NNN
3987** <li> :VVV
3988** <li> @VVV
3989** <li> $VVV
3990** </ul>
3992** In the templates above, NNN represents an integer literal,
3993** and VVV represents an alphanumeric identifier.)^ ^The values of these
3994** parameters (also called "host parameter names" or "SQL parameters")
3995** can be set using the sqlite3_bind_*() routines defined here.
3997** ^The first argument to the sqlite3_bind_*() routines is always
3998** a pointer to the [sqlite3_stmt] object returned from
3999** [sqlite3_prepare_v2()] or its variants.
4001** ^The second argument is the index of the SQL parameter to be set.
4002** ^The leftmost SQL parameter has an index of 1. ^When the same named
4003** SQL parameter is used more than once, second and subsequent
4004** occurrences have the same index as the first occurrence.
4005** ^The index for named parameters can be looked up using the
4006** [sqlite3_bind_parameter_index()] API if desired. ^The index
4007** for "?NNN" parameters is the value of NNN.
4008** ^The NNN value must be between 1 and the [sqlite3_limit()]
4009** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
4011** ^The third argument is the value to bind to the parameter.
4012** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
4013** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
4014** is ignored and the end result is the same as sqlite3_bind_null().
4016** ^(In those routines that have a fourth argument, its value is the
4017** number of bytes in the parameter. To be clear: the value is the
4018** number of <u>bytes</u> in the value, not the number of characters.)^
4019** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
4020** is negative, then the length of the string is
4021** the number of bytes up to the first zero terminator.
4022** If the fourth parameter to sqlite3_bind_blob() is negative, then
4023** the behavior is undefined.
4024** If a non-negative fourth parameter is provided to sqlite3_bind_text()
4025** or sqlite3_bind_text16() or sqlite3_bind_text64() then
4026** that parameter must be the byte offset
4027** where the NUL terminator would occur assuming the string were NUL
4028** terminated. If any NUL characters occur at byte offsets less than
4029** the value of the fourth parameter then the resulting string value will
4030** contain embedded NULs. The result of expressions involving strings
4031** with embedded NULs is undefined.
4033** ^The fifth argument to the BLOB and string binding interfaces
4034** is a destructor used to dispose of the BLOB or
4035** string after SQLite has finished with it. ^The destructor is called
4036** to dispose of the BLOB or string even if the call to bind API fails.
4037** ^If the fifth argument is
4038** the special value [SQLITE_STATIC], then SQLite assumes that the
4039** information is in static, unmanaged space and does not need to be freed.
4040** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
4041** SQLite makes its own private copy of the data immediately, before
4042** the sqlite3_bind_*() routine returns.
4044** ^The sixth argument to sqlite3_bind_text64() must be one of
4046** to specify the encoding of the text in the third parameter. If
4047** the sixth argument to sqlite3_bind_text64() is not one of the
4048** allowed values shown above, or if the text encoding is different
4049** from the encoding specified by the sixth parameter, then the behavior
4050** is undefined.
4052** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
4053** is filled with zeroes. ^A zeroblob uses a fixed amount of memory
4054** (just an integer to hold its size) while it is being processed.
4055** Zeroblobs are intended to serve as placeholders for BLOBs whose
4056** content is later written using
4057** [sqlite3_blob_open | incremental BLOB I/O] routines.
4058** ^A negative value for the zeroblob results in a zero-length BLOB.
4060** ^The sqlite3_bind_pointer(S,I,P,T,D) routine causes the I-th parameter in
4061** [prepared statement] S to have an SQL value of NULL, but to also be
4062** associated with the pointer P of type T. ^D is either a NULL pointer or
4063** a pointer to a destructor function for P. ^SQLite will invoke the
4064** destructor D with a single argument of P when it is finished using
4065** P. The T parameter should be a static string, preferably a string
4066** literal. The sqlite3_bind_pointer() routine is part of the
4067** [pointer passing interface] added for SQLite 3.20.0.
4069** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
4070** for the [prepared statement] or with a prepared statement for which
4071** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
4072** then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_()
4073** routine is passed a [prepared statement] that has been finalized, the
4074** result is undefined and probably harmful.
4076** ^Bindings are not cleared by the [sqlite3_reset()] routine.
4077** ^Unbound parameters are interpreted as NULL.
4079** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
4080** [error code] if anything goes wrong.
4081** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
4082** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
4084** ^[SQLITE_RANGE] is returned if the parameter
4085** index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails.
4087** See also: [sqlite3_bind_parameter_count()],
4088** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
4090SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
4091SQLITE_API int sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
4092 void(*)(void*));
4093SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
4094SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
4095SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
4096SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
4097SQLITE_API int sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
4098SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
4099SQLITE_API int sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
4100 void(*)(void*), unsigned char encoding);
4101SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
4102SQLITE_API int sqlite3_bind_pointer(sqlite3_stmt*, int, void*, const char*,void(*)(void*));
4103SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
4104SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
4107** CAPI3REF: Number Of SQL Parameters
4108** METHOD: sqlite3_stmt
4110** ^This routine can be used to find the number of [SQL parameters]
4111** in a [prepared statement]. SQL parameters are tokens of the
4112** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
4113** placeholders for values that are [sqlite3_bind_blob | bound]
4114** to the parameters at a later time.
4116** ^(This routine actually returns the index of the largest (rightmost)
4117** parameter. For all forms except ?NNN, this will correspond to the
4118** number of unique parameters. If parameters of the ?NNN form are used,
4119** there may be gaps in the list.)^
4121** See also: [sqlite3_bind_blob|sqlite3_bind()],
4122** [sqlite3_bind_parameter_name()], and
4123** [sqlite3_bind_parameter_index()].
4125SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
4128** CAPI3REF: Name Of A Host Parameter
4129** METHOD: sqlite3_stmt
4131** ^The sqlite3_bind_parameter_name(P,N) interface returns
4132** the name of the N-th [SQL parameter] in the [prepared statement] P.
4133** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
4134** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
4135** respectively.
4136** In other words, the initial ":" or "$" or "@" or "?"
4137** is included as part of the name.)^
4138** ^Parameters of the form "?" without a following integer have no name
4139** and are referred to as "nameless" or "anonymous parameters".
4141** ^The first host parameter has an index of 1, not 0.
4143** ^If the value N is out of range or if the N-th parameter is
4144** nameless, then NULL is returned. ^The returned string is
4145** always in UTF-8 encoding even if the named parameter was
4146** originally specified as UTF-16 in [sqlite3_prepare16()],
4147** [sqlite3_prepare16_v2()], or [sqlite3_prepare16_v3()].
4149** See also: [sqlite3_bind_blob|sqlite3_bind()],
4150** [sqlite3_bind_parameter_count()], and
4151** [sqlite3_bind_parameter_index()].
4153SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
4156** CAPI3REF: Index Of A Parameter With A Given Name
4157** METHOD: sqlite3_stmt
4159** ^Return the index of an SQL parameter given its name. ^The
4160** index value returned is suitable for use as the second
4161** parameter to [sqlite3_bind_blob|sqlite3_bind()]. ^A zero
4162** is returned if no matching parameter is found. ^The parameter
4163** name must be given in UTF-8 even if the original statement
4164** was prepared from UTF-16 text using [sqlite3_prepare16_v2()] or
4165** [sqlite3_prepare16_v3()].
4167** See also: [sqlite3_bind_blob|sqlite3_bind()],
4168** [sqlite3_bind_parameter_count()], and
4169** [sqlite3_bind_parameter_name()].
4171SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
4174** CAPI3REF: Reset All Bindings On A Prepared Statement
4175** METHOD: sqlite3_stmt
4177** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
4178** the [sqlite3_bind_blob | bindings] on a [prepared statement].
4179** ^Use this routine to reset all host parameters to NULL.
4181SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
4184** CAPI3REF: Number Of Columns In A Result Set
4185** METHOD: sqlite3_stmt
4187** ^Return the number of columns in the result set returned by the
4188** [prepared statement]. ^If this routine returns 0, that means the
4189** [prepared statement] returns no data (for example an [UPDATE]).
4190** ^However, just because this routine returns a positive number does not
4191** mean that one or more rows of data will be returned. ^A SELECT statement
4192** will always have a positive sqlite3_column_count() but depending on the
4193** WHERE clause constraints and the table content, it might return no rows.
4195** See also: [sqlite3_data_count()]
4197SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
4200** CAPI3REF: Column Names In A Result Set
4201** METHOD: sqlite3_stmt
4203** ^These routines return the name assigned to a particular column
4204** in the result set of a [SELECT] statement. ^The sqlite3_column_name()
4205** interface returns a pointer to a zero-terminated UTF-8 string
4206** and sqlite3_column_name16() returns a pointer to a zero-terminated
4207** UTF-16 string. ^The first parameter is the [prepared statement]
4208** that implements the [SELECT] statement. ^The second parameter is the
4209** column number. ^The leftmost column is number 0.
4211** ^The returned string pointer is valid until either the [prepared statement]
4212** is destroyed by [sqlite3_finalize()] or until the statement is automatically
4213** reprepared by the first call to [sqlite3_step()] for a particular run
4214** or until the next call to
4215** sqlite3_column_name() or sqlite3_column_name16() on the same column.
4217** ^If sqlite3_malloc() fails during the processing of either routine
4218** (for example during a conversion from UTF-8 to UTF-16) then a
4219** NULL pointer is returned.
4221** ^The name of a result column is the value of the "AS" clause for
4222** that column, if there is an AS clause. If there is no AS clause
4223** then the name of the column is unspecified and may change from
4224** one release of SQLite to the next.
4226SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
4227SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
4230** CAPI3REF: Source Of Data In A Query Result
4231** METHOD: sqlite3_stmt
4233** ^These routines provide a means to determine the database, table, and
4234** table column that is the origin of a particular result column in
4235** [SELECT] statement.
4236** ^The name of the database or table or column can be returned as
4237** either a UTF-8 or UTF-16 string. ^The _database_ routines return
4238** the database name, the _table_ routines return the table name, and
4239** the origin_ routines return the column name.
4240** ^The returned string is valid until the [prepared statement] is destroyed
4241** using [sqlite3_finalize()] or until the statement is automatically
4242** reprepared by the first call to [sqlite3_step()] for a particular run
4243** or until the same information is requested
4244** again in a different encoding.
4246** ^The names returned are the original un-aliased names of the
4247** database, table, and column.
4249** ^The first argument to these interfaces is a [prepared statement].
4250** ^These functions return information about the Nth result column returned by
4251** the statement, where N is the second function argument.
4252** ^The left-most column is column 0 for these routines.
4254** ^If the Nth column returned by the statement is an expression or
4255** subquery and is not a column value, then all of these functions return
4256** NULL. ^These routine might also return NULL if a memory allocation error
4257** occurs. ^Otherwise, they return the name of the attached database, table,
4258** or column that query result column was extracted from.
4260** ^As with all other SQLite APIs, those whose names end with "16" return
4261** UTF-16 encoded strings and the other functions return UTF-8.
4263** ^These APIs are only available if the library was compiled with the
4264** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
4266** If two or more threads call one or more of these routines against the same
4267** prepared statement and column at the same time then the results are
4268** undefined.
4270** If two or more threads call one or more
4271** [sqlite3_column_database_name | column metadata interfaces]
4272** for the same [prepared statement] and result column
4273** at the same time then the results are undefined.
4275SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
4276SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
4277SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
4278SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
4279SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
4280SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
4283** CAPI3REF: Declared Datatype Of A Query Result
4284** METHOD: sqlite3_stmt
4286** ^(The first parameter is a [prepared statement].
4287** If this statement is a [SELECT] statement and the Nth column of the
4288** returned result set of that [SELECT] is a table column (not an
4289** expression or subquery) then the declared type of the table
4290** column is returned.)^ ^If the Nth column of the result set is an
4291** expression or subquery, then a NULL pointer is returned.
4292** ^The returned string is always UTF-8 encoded.
4294** ^(For example, given the database schema:
4298** and the following statement to be compiled:
4300** SELECT c1 + 1, c1 FROM t1;
4302** this routine would return the string "VARIANT" for the second result
4303** column (i==1), and a NULL pointer for the first result column (i==0).)^
4305** ^SQLite uses dynamic run-time typing. ^So just because a column
4306** is declared to contain a particular type does not mean that the
4307** data stored in that column is of the declared type. SQLite is
4308** strongly typed, but the typing is dynamic not static. ^Type
4309** is associated with individual values, not with the containers
4310** used to hold those values.
4312SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
4313SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
4316** CAPI3REF: Evaluate An SQL Statement
4317** METHOD: sqlite3_stmt
4319** After a [prepared statement] has been prepared using any of
4320** [sqlite3_prepare_v2()], [sqlite3_prepare_v3()], [sqlite3_prepare16_v2()],
4321** or [sqlite3_prepare16_v3()] or one of the legacy
4322** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
4323** must be called one or more times to evaluate the statement.
4325** The details of the behavior of the sqlite3_step() interface depend
4326** on whether the statement was prepared using the newer "vX" interfaces
4327** [sqlite3_prepare_v3()], [sqlite3_prepare_v2()], [sqlite3_prepare16_v3()],
4328** [sqlite3_prepare16_v2()] or the older legacy
4329** interfaces [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the
4330** new "vX" interface is recommended for new applications but the legacy
4331** interface will continue to be supported.
4333** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
4335** ^With the "v2" interface, any of the other [result codes] or
4336** [extended result codes] might be returned as well.
4338** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
4339** database locks it needs to do its job. ^If the statement is a [COMMIT]
4340** or occurs outside of an explicit transaction, then you can retry the
4341** statement. If the statement is not a [COMMIT] and occurs within an
4342** explicit transaction then you should rollback the transaction before
4343** continuing.
4345** ^[SQLITE_DONE] means that the statement has finished executing
4346** successfully. sqlite3_step() should not be called again on this virtual
4347** machine without first calling [sqlite3_reset()] to reset the virtual
4348** machine back to its initial state.
4350** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
4351** is returned each time a new row of data is ready for processing by the
4352** caller. The values may be accessed using the [column access functions].
4353** sqlite3_step() is called again to retrieve the next row of data.
4355** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
4356** violation) has occurred. sqlite3_step() should not be called again on
4357** the VM. More information may be found by calling [sqlite3_errmsg()].
4358** ^With the legacy interface, a more specific error code (for example,
4360** can be obtained by calling [sqlite3_reset()] on the
4361** [prepared statement]. ^In the "v2" interface,
4362** the more specific error code is returned directly by sqlite3_step().
4364** [SQLITE_MISUSE] means that the this routine was called inappropriately.
4365** Perhaps it was called on a [prepared statement] that has
4366** already been [sqlite3_finalize | finalized] or on one that had
4367** previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could
4368** be the case that the same database connection is being used by two or
4369** more threads at the same moment in time.
4371** For all versions of SQLite up to and including, a call to
4372** [sqlite3_reset()] was required after sqlite3_step() returned anything
4373** other than [SQLITE_ROW] before any subsequent invocation of
4374** sqlite3_step(). Failure to reset the prepared statement using
4375** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
4376** sqlite3_step(). But after [version] ([dateof:],
4377** sqlite3_step() began
4378** calling [sqlite3_reset()] automatically in this circumstance rather
4379** than returning [SQLITE_MISUSE]. This is not considered a compatibility
4380** break because any application that ever receives an SQLITE_MISUSE error
4381** is broken by definition. The [SQLITE_OMIT_AUTORESET] compile-time option
4382** can be used to restore the legacy behavior.
4384** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
4385** API always returns a generic error code, [SQLITE_ERROR], following any
4386** error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call
4387** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
4388** specific [error codes] that better describes the error.
4389** We admit that this is a goofy design. The problem has been fixed
4390** with the "v2" interface. If you prepare all of your SQL statements
4391** using [sqlite3_prepare_v3()] or [sqlite3_prepare_v2()]
4392** or [sqlite3_prepare16_v2()] or [sqlite3_prepare16_v3()] instead
4393** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
4394** then the more specific [error codes] are returned directly
4395** by sqlite3_step(). The use of the "vX" interfaces is recommended.
4397SQLITE_API int sqlite3_step(sqlite3_stmt*);
4400** CAPI3REF: Number of columns in a result set
4401** METHOD: sqlite3_stmt
4403** ^The sqlite3_data_count(P) interface returns the number of columns in the
4404** current row of the result set of [prepared statement] P.
4405** ^If prepared statement P does not have results ready to return
4406** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
4407** interfaces) then sqlite3_data_count(P) returns 0.
4408** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
4409** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
4410** [sqlite3_step](P) returned [SQLITE_DONE]. ^The sqlite3_data_count(P)
4411** will return non-zero if previous call to [sqlite3_step](P) returned
4412** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
4413** where it always returns zero since each step of that multi-step
4414** pragma returns 0 columns of data.
4416** See also: [sqlite3_column_count()]
4418SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
4421** CAPI3REF: Fundamental Datatypes
4424** ^(Every value in SQLite has one of five fundamental datatypes:
4426** <ul>
4427** <li> 64-bit signed integer
4428** <li> 64-bit IEEE floating point number
4429** <li> string
4430** <li> BLOB
4431** <li> NULL
4432** </ul>)^
4434** These constants are codes for each of those types.
4436** Note that the SQLITE_TEXT constant was also used in SQLite version 2
4437** for a completely different meaning. Software that links against both
4438** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
4441#define SQLITE_INTEGER 1
4442#define SQLITE_FLOAT 2
4443#define SQLITE_BLOB 4
4444#define SQLITE_NULL 5
4445#ifdef SQLITE_TEXT
4446# undef SQLITE_TEXT
4448# define SQLITE_TEXT 3
4450#define SQLITE3_TEXT 3
4453** CAPI3REF: Result Values From A Query
4454** KEYWORDS: {column access functions}
4455** METHOD: sqlite3_stmt
4457** <b>Summary:</b>
4458** <blockquote><table border=0 cellpadding=0 cellspacing=0>
4459** <tr><td><b>sqlite3_column_blob</b><td>&rarr;<td>BLOB result
4460** <tr><td><b>sqlite3_column_double</b><td>&rarr;<td>REAL result
4461** <tr><td><b>sqlite3_column_int</b><td>&rarr;<td>32-bit INTEGER result
4462** <tr><td><b>sqlite3_column_int64</b><td>&rarr;<td>64-bit INTEGER result
4463** <tr><td><b>sqlite3_column_text</b><td>&rarr;<td>UTF-8 TEXT result
4464** <tr><td><b>sqlite3_column_text16</b><td>&rarr;<td>UTF-16 TEXT result
4465** <tr><td><b>sqlite3_column_value</b><td>&rarr;<td>The result as an
4466** [sqlite3_value|unprotected sqlite3_value] object.
4467** <tr><td>&nbsp;<td>&nbsp;<td>&nbsp;
4468** <tr><td><b>sqlite3_column_bytes</b><td>&rarr;<td>Size of a BLOB
4469** or a UTF-8 TEXT result in bytes
4470** <tr><td><b>sqlite3_column_bytes16&nbsp;&nbsp;</b>
4471** <td>&rarr;&nbsp;&nbsp;<td>Size of UTF-16
4472** TEXT in bytes
4473** <tr><td><b>sqlite3_column_type</b><td>&rarr;<td>Default
4474** datatype of the result
4475** </table></blockquote>
4477** <b>Details:</b>
4479** ^These routines return information about a single column of the current
4480** result row of a query. ^In every case the first argument is a pointer
4481** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
4482** that was returned from [sqlite3_prepare_v2()] or one of its variants)
4483** and the second argument is the index of the column for which information
4484** should be returned. ^The leftmost column of the result set has the index 0.
4485** ^The number of columns in the result can be determined using
4486** [sqlite3_column_count()].
4488** If the SQL statement does not currently point to a valid row, or if the
4489** column index is out of range, the result is undefined.
4490** These routines may only be called when the most recent call to
4491** [sqlite3_step()] has returned [SQLITE_ROW] and neither
4492** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
4493** If any of these routines are called after [sqlite3_reset()] or
4494** [sqlite3_finalize()] or after [sqlite3_step()] has returned
4495** something other than [SQLITE_ROW], the results are undefined.
4496** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
4497** are called from a different thread while any of these routines
4498** are pending, then the results are undefined.
4500** The first six interfaces (_blob, _double, _int, _int64, _text, and _text16)
4501** each return the value of a result column in a specific data format. If
4502** the result column is not initially in the requested format (for example,
4503** if the query returns an integer but the sqlite3_column_text() interface
4504** is used to extract the value) then an automatic type conversion is performed.
4506** ^The sqlite3_column_type() routine returns the
4507** [SQLITE_INTEGER | datatype code] for the initial data type
4508** of the result column. ^The returned value is one of [SQLITE_INTEGER],
4510** The return value of sqlite3_column_type() can be used to decide which
4511** of the first six interface should be used to extract the column value.
4512** The value returned by sqlite3_column_type() is only meaningful if no
4513** automatic type conversions have occurred for the value in question.
4514** After a type conversion, the result of calling sqlite3_column_type()
4515** is undefined, though harmless. Future
4516** versions of SQLite may change the behavior of sqlite3_column_type()
4517** following a type conversion.
4519** If the result is a BLOB or a TEXT string, then the sqlite3_column_bytes()
4520** or sqlite3_column_bytes16() interfaces can be used to determine the size
4521** of that BLOB or string.
4523** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
4524** routine returns the number of bytes in that BLOB or string.
4525** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
4526** the string to UTF-8 and then returns the number of bytes.
4527** ^If the result is a numeric value then sqlite3_column_bytes() uses
4528** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
4529** the number of bytes in that string.
4530** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
4532** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
4533** routine returns the number of bytes in that BLOB or string.
4534** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
4535** the string to UTF-16 and then returns the number of bytes.
4536** ^If the result is a numeric value then sqlite3_column_bytes16() uses
4537** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
4538** the number of bytes in that string.
4539** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
4541** ^The values returned by [sqlite3_column_bytes()] and
4542** [sqlite3_column_bytes16()] do not include the zero terminators at the end
4543** of the string. ^For clarity: the values returned by
4544** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
4545** bytes in the string, not the number of characters.
4547** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
4548** even empty strings, are always zero-terminated. ^The return
4549** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
4551** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
4552** [unprotected sqlite3_value] object. In a multithreaded environment,
4553** an unprotected sqlite3_value object may only be used safely with
4554** [sqlite3_bind_value()] and [sqlite3_result_value()].
4555** If the [unprotected sqlite3_value] object returned by
4556** [sqlite3_column_value()] is used in any other way, including calls
4557** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
4558** or [sqlite3_value_bytes()], the behavior is not threadsafe.
4559** Hence, the sqlite3_column_value() interface
4560** is normally only useful within the implementation of
4561** [application-defined SQL functions] or [virtual tables], not within
4562** top-level application code.
4564** The these routines may attempt to convert the datatype of the result.
4565** ^For example, if the internal representation is FLOAT and a text result
4566** is requested, [sqlite3_snprintf()] is used internally to perform the
4567** conversion automatically. ^(The following table details the conversions
4568** that are applied:
4570** <blockquote>
4571** <table border="1">
4572** <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion
4574** <tr><td> NULL <td> INTEGER <td> Result is 0
4575** <tr><td> NULL <td> FLOAT <td> Result is 0.0
4576** <tr><td> NULL <td> TEXT <td> Result is a NULL pointer
4577** <tr><td> NULL <td> BLOB <td> Result is a NULL pointer
4578** <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float
4579** <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer
4580** <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT
4581** <tr><td> FLOAT <td> INTEGER <td> [CAST] to INTEGER
4582** <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float
4583** <tr><td> FLOAT <td> BLOB <td> [CAST] to BLOB
4584** <tr><td> TEXT <td> INTEGER <td> [CAST] to INTEGER
4585** <tr><td> TEXT <td> FLOAT <td> [CAST] to REAL
4586** <tr><td> TEXT <td> BLOB <td> No change
4587** <tr><td> BLOB <td> INTEGER <td> [CAST] to INTEGER
4588** <tr><td> BLOB <td> FLOAT <td> [CAST] to REAL
4589** <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed
4590** </table>
4591** </blockquote>)^
4593** Note that when type conversions occur, pointers returned by prior
4594** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
4595** sqlite3_column_text16() may be invalidated.
4596** Type conversions and pointer invalidations might occur
4597** in the following cases:
4599** <ul>
4600** <li> The initial content is a BLOB and sqlite3_column_text() or
4601** sqlite3_column_text16() is called. A zero-terminator might
4602** need to be added to the string.</li>
4603** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
4604** sqlite3_column_text16() is called. The content must be converted
4605** to UTF-16.</li>
4606** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
4607** sqlite3_column_text() is called. The content must be converted
4608** to UTF-8.</li>
4609** </ul>
4611** ^Conversions between UTF-16be and UTF-16le are always done in place and do
4612** not invalidate a prior pointer, though of course the content of the buffer
4613** that the prior pointer references will have been modified. Other kinds
4614** of conversion are done in place when it is possible, but sometimes they
4615** are not possible and in those cases prior pointers are invalidated.
4617** The safest policy is to invoke these routines
4618** in one of the following ways:
4620** <ul>
4621** <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
4622** <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
4623** <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
4624** </ul>
4626** In other words, you should call sqlite3_column_text(),
4627** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
4628** into the desired format, then invoke sqlite3_column_bytes() or
4629** sqlite3_column_bytes16() to find the size of the result. Do not mix calls
4630** to sqlite3_column_text() or sqlite3_column_blob() with calls to
4631** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
4632** with calls to sqlite3_column_bytes().
4634** ^The pointers returned are valid until a type conversion occurs as
4635** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
4636** [sqlite3_finalize()] is called. ^The memory space used to hold strings
4637** and BLOBs is freed automatically. Do not pass the pointers returned
4638** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
4639** [sqlite3_free()].
4641** As long as the input parameters are correct, these routines will only
4642** fail if an out-of-memory error occurs during a format conversion.
4643** Only the following subset of interfaces are subject to out-of-memory
4644** errors:
4646** <ul>
4647** <li> sqlite3_column_blob()
4648** <li> sqlite3_column_text()
4649** <li> sqlite3_column_text16()
4650** <li> sqlite3_column_bytes()
4651** <li> sqlite3_column_bytes16()
4652** </ul>
4654** If an out-of-memory error occurs, then the return value from these
4655** routines is the same as if the column had contained an SQL NULL value.
4656** Valid SQL NULL returns can be distinguished from out-of-memory errors
4657** by invoking the [sqlite3_errcode()] immediately after the suspect
4658** return value is obtained and before any
4659** other SQLite interface is called on the same [database connection].
4661SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
4662SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
4663SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
4664SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
4665SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
4666SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
4667SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
4668SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
4669SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
4670SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
4673** CAPI3REF: Destroy A Prepared Statement Object
4674** DESTRUCTOR: sqlite3_stmt
4676** ^The sqlite3_finalize() function is called to delete a [prepared statement].
4677** ^If the most recent evaluation of the statement encountered no errors
4678** or if the statement is never been evaluated, then sqlite3_finalize() returns
4679** SQLITE_OK. ^If the most recent evaluation of statement S failed, then
4680** sqlite3_finalize(S) returns the appropriate [error code] or
4681** [extended error code].
4683** ^The sqlite3_finalize(S) routine can be called at any point during
4684** the life cycle of [prepared statement] S:
4685** before statement S is ever evaluated, after
4686** one or more calls to [sqlite3_reset()], or after any call
4687** to [sqlite3_step()] regardless of whether or not the statement has
4688** completed execution.
4690** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
4692** The application must finalize every [prepared statement] in order to avoid
4693** resource leaks. It is a grievous error for the application to try to use
4694** a prepared statement after it has been finalized. Any use of a prepared
4695** statement after it has been finalized can result in undefined and
4696** undesirable behavior such as segfaults and heap corruption.
4698SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
4701** CAPI3REF: Reset A Prepared Statement Object
4702** METHOD: sqlite3_stmt
4704** The sqlite3_reset() function is called to reset a [prepared statement]
4705** object back to its initial state, ready to be re-executed.
4706** ^Any SQL statement variables that had values bound to them using
4707** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
4708** Use [sqlite3_clear_bindings()] to reset the bindings.
4710** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
4711** back to the beginning of its program.
4713** ^If the most recent call to [sqlite3_step(S)] for the
4714** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
4715** or if [sqlite3_step(S)] has never before been called on S,
4716** then [sqlite3_reset(S)] returns [SQLITE_OK].
4718** ^If the most recent call to [sqlite3_step(S)] for the
4719** [prepared statement] S indicated an error, then
4720** [sqlite3_reset(S)] returns an appropriate [error code].
4722** ^The [sqlite3_reset(S)] interface does not change the values
4723** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
4725SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
4728** CAPI3REF: Create Or Redefine SQL Functions
4729** KEYWORDS: {function creation routines}
4730** KEYWORDS: {application-defined SQL function}
4731** KEYWORDS: {application-defined SQL functions}
4732** METHOD: sqlite3
4734** ^These functions (collectively known as "function creation routines")
4735** are used to add SQL functions or aggregates or to redefine the behavior
4736** of existing SQL functions or aggregates. The only differences between
4737** the three "sqlite3_create_function*" routines are the text encoding
4738** expected for the second parameter (the name of the function being
4739** created) and the presence or absence of a destructor callback for
4740** the application data pointer. Function sqlite3_create_window_function()
4741** is similar, but allows the user to supply the extra callback functions
4742** needed by [aggregate window functions].
4744** ^The first parameter is the [database connection] to which the SQL
4745** function is to be added. ^If an application uses more than one database
4746** connection then application-defined SQL functions must be added
4747** to each database connection separately.
4749** ^The second parameter is the name of the SQL function to be created or
4750** redefined. ^The length of the name is limited to 255 bytes in a UTF-8
4751** representation, exclusive of the zero-terminator. ^Note that the name
4752** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.
4753** ^Any attempt to create a function with a longer name
4754** will result in [SQLITE_MISUSE] being returned.
4756** ^The third parameter (nArg)
4757** is the number of arguments that the SQL function or
4758** aggregate takes. ^If this parameter is -1, then the SQL function or
4759** aggregate may take any number of arguments between 0 and the limit
4760** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third
4761** parameter is less than -1 or greater than 127 then the behavior is
4762** undefined.
4764** ^The fourth parameter, eTextRep, specifies what
4765** [SQLITE_UTF8 | text encoding] this SQL function prefers for
4766** its parameters. The application should set this parameter to
4767** [SQLITE_UTF16LE] if the function implementation invokes
4768** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
4769** implementation invokes [sqlite3_value_text16be()] on an input, or
4770** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
4771** otherwise. ^The same SQL function may be registered multiple times using
4772** different preferred text encodings, with different implementations for
4773** each encoding.
4774** ^When multiple implementations of the same function are available, SQLite
4775** will pick the one that involves the least amount of data conversion.
4777** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
4778** to signal that the function will always return the same result given
4779** the same inputs within a single SQL statement. Most SQL functions are
4780** deterministic. The built-in [random()] SQL function is an example of a
4781** function that is not deterministic. The SQLite query planner is able to
4782** perform additional optimizations on deterministic functions, so use
4783** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
4785** ^(The fifth parameter is an arbitrary pointer. The implementation of the
4786** function can gain access to this pointer using [sqlite3_user_data()].)^
4788** ^The sixth, seventh and eighth parameters passed to the three
4789** "sqlite3_create_function*" functions, xFunc, xStep and xFinal, are
4790** pointers to C-language functions that implement the SQL function or
4791** aggregate. ^A scalar SQL function requires an implementation of the xFunc
4792** callback only; NULL pointers must be passed as the xStep and xFinal
4793** parameters. ^An aggregate SQL function requires an implementation of xStep
4794** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
4795** SQL function or aggregate, pass NULL pointers for all three function
4796** callbacks.
4798** ^The sixth, seventh, eighth and ninth parameters (xStep, xFinal, xValue
4799** and xInverse) passed to sqlite3_create_window_function are pointers to
4800** C-language callbacks that implement the new function. xStep and xFinal
4801** must both be non-NULL. xValue and xInverse may either both be NULL, in
4802** which case a regular aggregate function is created, or must both be
4803** non-NULL, in which case the new function may be used as either an aggregate
4804** or aggregate window function. More details regarding the implementation
4805** of aggregate window functions are
4806** [user-defined window functions|available here].
4808** ^(If the final parameter to sqlite3_create_function_v2() or
4809** sqlite3_create_window_function() is not NULL, then it is destructor for
4810** the application data pointer. The destructor is invoked when the function
4811** is deleted, either by being overloaded or when the database connection
4812** closes.)^ ^The destructor is also invoked if the call to
4813** sqlite3_create_function_v2() fails. ^When the destructor callback is
4814** invoked, it is passed a single argument which is a copy of the application
4815** data pointer which was the fifth parameter to sqlite3_create_function_v2().
4817** ^It is permitted to register multiple implementations of the same
4818** functions with the same name but with either differing numbers of
4819** arguments or differing preferred text encodings. ^SQLite will use
4820** the implementation that most closely matches the way in which the
4821** SQL function is used. ^A function implementation with a non-negative
4822** nArg parameter is a better match than a function implementation with
4823** a negative nArg. ^A function where the preferred text encoding
4824** matches the database encoding is a better
4825** match than a function where the encoding is different.
4826** ^A function where the encoding difference is between UTF16le and UTF16be
4827** is a closer match than a function where the encoding difference is
4828** between UTF8 and UTF16.
4830** ^Built-in functions may be overloaded by new application-defined functions.
4832** ^An application-defined function is permitted to call other
4833** SQLite interfaces. However, such calls must not
4834** close the database connection nor finalize or reset the prepared
4835** statement in which the function is running.
4837SQLITE_API int sqlite3_create_function(
4838 sqlite3 *db,
4839 const char *zFunctionName,
4840 int nArg,
4841 int eTextRep,
4842 void *pApp,
4843 void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4844 void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4845 void (*xFinal)(sqlite3_context*)
4847SQLITE_API int sqlite3_create_function16(
4848 sqlite3 *db,
4849 const void *zFunctionName,
4850 int nArg,
4851 int eTextRep,
4852 void *pApp,
4853 void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4854 void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4855 void (*xFinal)(sqlite3_context*)
4857SQLITE_API int sqlite3_create_function_v2(
4858 sqlite3 *db,
4859 const char *zFunctionName,
4860 int nArg,
4861 int eTextRep,
4862 void *pApp,
4863 void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4864 void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4865 void (*xFinal)(sqlite3_context*),
4866 void(*xDestroy)(void*)
4868SQLITE_API int sqlite3_create_window_function(
4869 sqlite3 *db,
4870 const char *zFunctionName,
4871 int nArg,
4872 int eTextRep,
4873 void *pApp,
4874 void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4875 void (*xFinal)(sqlite3_context*),
4876 void (*xValue)(sqlite3_context*),
4877 void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
4878 void(*xDestroy)(void*)
4882** CAPI3REF: Text Encodings
4884** These constant define integer codes that represent the various
4885** text encodings supported by SQLite.
4887#define SQLITE_UTF8 1 /* IMP: R-37514-35566 */
4888#define SQLITE_UTF16LE 2 /* IMP: R-03371-37637 */
4889#define SQLITE_UTF16BE 3 /* IMP: R-51971-34154 */
4890#define SQLITE_UTF16 4 /* Use native byte order */
4891#define SQLITE_ANY 5 /* Deprecated */
4892#define SQLITE_UTF16_ALIGNED 8 /* sqlite3_create_collation only */
4895** CAPI3REF: Function Flags
4897** These constants may be ORed together with the
4898** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
4899** to [sqlite3_create_function()], [sqlite3_create_function16()], or
4900** [sqlite3_create_function_v2()].
4902#define SQLITE_DETERMINISTIC 0x800
4905** CAPI3REF: Deprecated Functions
4908** These functions are [deprecated]. In order to maintain
4909** backwards compatibility with older code, these functions continue
4910** to be supported. However, new applications should avoid
4911** the use of these functions. To encourage programmers to avoid
4912** these functions, we will not explain what they do.
4915SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
4916SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
4917SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
4918SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
4919SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
4920SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
4921 void*,sqlite3_int64);
4925** CAPI3REF: Obtaining SQL Values
4926** METHOD: sqlite3_value
4928** <b>Summary:</b>
4929** <blockquote><table border=0 cellpadding=0 cellspacing=0>
4930** <tr><td><b>sqlite3_value_blob</b><td>&rarr;<td>BLOB value
4931** <tr><td><b>sqlite3_value_double</b><td>&rarr;<td>REAL value
4932** <tr><td><b>sqlite3_value_int</b><td>&rarr;<td>32-bit INTEGER value
4933** <tr><td><b>sqlite3_value_int64</b><td>&rarr;<td>64-bit INTEGER value
4934** <tr><td><b>sqlite3_value_pointer</b><td>&rarr;<td>Pointer value
4935** <tr><td><b>sqlite3_value_text</b><td>&rarr;<td>UTF-8 TEXT value
4936** <tr><td><b>sqlite3_value_text16</b><td>&rarr;<td>UTF-16 TEXT value in
4937** the native byteorder
4938** <tr><td><b>sqlite3_value_text16be</b><td>&rarr;<td>UTF-16be TEXT value
4939** <tr><td><b>sqlite3_value_text16le</b><td>&rarr;<td>UTF-16le TEXT value
4940** <tr><td>&nbsp;<td>&nbsp;<td>&nbsp;
4941** <tr><td><b>sqlite3_value_bytes</b><td>&rarr;<td>Size of a BLOB
4942** or a UTF-8 TEXT in bytes
4943** <tr><td><b>sqlite3_value_bytes16&nbsp;&nbsp;</b>
4944** <td>&rarr;&nbsp;&nbsp;<td>Size of UTF-16
4945** TEXT in bytes
4946** <tr><td><b>sqlite3_value_type</b><td>&rarr;<td>Default
4947** datatype of the value
4948** <tr><td><b>sqlite3_value_numeric_type&nbsp;&nbsp;</b>
4949** <td>&rarr;&nbsp;&nbsp;<td>Best numeric datatype of the value
4950** <tr><td><b>sqlite3_value_nochange&nbsp;&nbsp;</b>
4951** <td>&rarr;&nbsp;&nbsp;<td>True if the column is unchanged in an UPDATE
4952** against a virtual table.
4953** </table></blockquote>
4955** <b>Details:</b>
4957** These routines extract type, size, and content information from
4958** [protected sqlite3_value] objects. Protected sqlite3_value objects
4959** are used to pass parameter information into implementation of
4960** [application-defined SQL functions] and [virtual tables].
4962** These routines work only with [protected sqlite3_value] objects.
4963** Any attempt to use these routines on an [unprotected sqlite3_value]
4964** is not threadsafe.
4966** ^These routines work just like the corresponding [column access functions]
4967** except that these routines take a single [protected sqlite3_value] object
4968** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
4970** ^The sqlite3_value_text16() interface extracts a UTF-16 string
4971** in the native byte-order of the host machine. ^The
4972** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
4973** extract UTF-16 strings as big-endian and little-endian respectively.
4975** ^If [sqlite3_value] object V was initialized
4976** using [sqlite3_bind_pointer(S,I,P,X,D)] or [sqlite3_result_pointer(C,P,X,D)]
4977** and if X and Y are strings that compare equal according to strcmp(X,Y),
4978** then sqlite3_value_pointer(V,Y) will return the pointer P. ^Otherwise,
4979** sqlite3_value_pointer(V,Y) returns a NULL. The sqlite3_bind_pointer()
4980** routine is part of the [pointer passing interface] added for SQLite 3.20.0.
4982** ^(The sqlite3_value_type(V) interface returns the
4983** [SQLITE_INTEGER | datatype code] for the initial datatype of the
4984** [sqlite3_value] object V. The returned value is one of [SQLITE_INTEGER],
4986** Other interfaces might change the datatype for an sqlite3_value object.
4987** For example, if the datatype is initially SQLITE_INTEGER and
4988** sqlite3_value_text(V) is called to extract a text value for that
4989** integer, then subsequent calls to sqlite3_value_type(V) might return
4990** SQLITE_TEXT. Whether or not a persistent internal datatype conversion
4991** occurs is undefined and may change from one release of SQLite to the next.
4993** ^(The sqlite3_value_numeric_type() interface attempts to apply
4994** numeric affinity to the value. This means that an attempt is
4995** made to convert the value to an integer or floating point. If
4996** such a conversion is possible without loss of information (in other
4997** words, if the value is a string that looks like a number)
4998** then the conversion is performed. Otherwise no conversion occurs.
4999** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
5001** ^Within the [xUpdate] method of a [virtual table], the
5002** sqlite3_value_nochange(X) interface returns true if and only if
5003** the column corresponding to X is unchanged by the UPDATE operation
5004** that the xUpdate method call was invoked to implement and if
5005** and the prior [xColumn] method call that was invoked to extracted
5006** the value for that column returned without setting a result (probably
5007** because it queried [sqlite3_vtab_nochange()] and found that the column
5008** was unchanging). ^Within an [xUpdate] method, any value for which
5009** sqlite3_value_nochange(X) is true will in all other respects appear
5010** to be a NULL value. If sqlite3_value_nochange(X) is invoked anywhere other
5011** than within an [xUpdate] method call for an UPDATE statement, then
5012** the return value is arbitrary and meaningless.
5014** Please pay particular attention to the fact that the pointer returned
5015** from [sqlite3_value_blob()], [sqlite3_value_text()], or
5016** [sqlite3_value_text16()] can be invalidated by a subsequent call to
5017** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
5018** or [sqlite3_value_text16()].
5020** These routines must be called from the same thread as
5021** the SQL function that supplied the [sqlite3_value*] parameters.
5023** As long as the input parameter is correct, these routines can only
5024** fail if an out-of-memory error occurs during a format conversion.
5025** Only the following subset of interfaces are subject to out-of-memory
5026** errors:
5028** <ul>
5029** <li> sqlite3_value_blob()
5030** <li> sqlite3_value_text()
5031** <li> sqlite3_value_text16()
5032** <li> sqlite3_value_text16le()
5033** <li> sqlite3_value_text16be()
5034** <li> sqlite3_value_bytes()
5035** <li> sqlite3_value_bytes16()
5036** </ul>
5038** If an out-of-memory error occurs, then the return value from these
5039** routines is the same as if the column had contained an SQL NULL value.
5040** Valid SQL NULL returns can be distinguished from out-of-memory errors
5041** by invoking the [sqlite3_errcode()] immediately after the suspect
5042** return value is obtained and before any
5043** other SQLite interface is called on the same [database connection].
5045SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
5046SQLITE_API double sqlite3_value_double(sqlite3_value*);
5047SQLITE_API int sqlite3_value_int(sqlite3_value*);
5048SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
5049SQLITE_API void *sqlite3_value_pointer(sqlite3_value*, const char*);
5050SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
5051SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
5052SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
5053SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
5054SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
5055SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
5056SQLITE_API int sqlite3_value_type(sqlite3_value*);
5057SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
5058SQLITE_API int sqlite3_value_nochange(sqlite3_value*);
5061** CAPI3REF: Finding The Subtype Of SQL Values
5062** METHOD: sqlite3_value
5064** The sqlite3_value_subtype(V) function returns the subtype for
5065** an [application-defined SQL function] argument V. The subtype
5066** information can be used to pass a limited amount of context from
5067** one SQL function to another. Use the [sqlite3_result_subtype()]
5068** routine to set the subtype for the return value of an SQL function.
5070SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value*);
5073** CAPI3REF: Copy And Free SQL Values
5074** METHOD: sqlite3_value
5076** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
5077** object D and returns a pointer to that copy. ^The [sqlite3_value] returned
5078** is a [protected sqlite3_value] object even if the input is not.
5079** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
5080** memory allocation fails.
5082** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
5083** previously obtained from [sqlite3_value_dup()]. ^If V is a NULL pointer
5084** then sqlite3_value_free(V) is a harmless no-op.
5086SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value*);
5087SQLITE_API void sqlite3_value_free(sqlite3_value*);
5090** CAPI3REF: Obtain Aggregate Function Context
5091** METHOD: sqlite3_context
5093** Implementations of aggregate SQL functions use this
5094** routine to allocate memory for storing their state.
5096** ^The first time the sqlite3_aggregate_context(C,N) routine is called
5097** for a particular aggregate function, SQLite
5098** allocates N of memory, zeroes out that memory, and returns a pointer
5099** to the new memory. ^On second and subsequent calls to
5100** sqlite3_aggregate_context() for the same aggregate function instance,
5101** the same buffer is returned. Sqlite3_aggregate_context() is normally
5102** called once for each invocation of the xStep callback and then one
5103** last time when the xFinal callback is invoked. ^(When no rows match
5104** an aggregate query, the xStep() callback of the aggregate function
5105** implementation is never called and xFinal() is called exactly once.
5106** In those cases, sqlite3_aggregate_context() might be called for the
5107** first time from within xFinal().)^
5109** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer
5110** when first called if N is less than or equal to zero or if a memory
5111** allocate error occurs.
5113** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
5114** determined by the N parameter on first successful call. Changing the
5115** value of N in subsequent call to sqlite3_aggregate_context() within
5116** the same aggregate function instance will not resize the memory
5117** allocation.)^ Within the xFinal callback, it is customary to set
5118** N=0 in calls to sqlite3_aggregate_context(C,N) so that no
5119** pointless memory allocations occur.
5121** ^SQLite automatically frees the memory allocated by
5122** sqlite3_aggregate_context() when the aggregate query concludes.
5124** The first parameter must be a copy of the
5125** [sqlite3_context | SQL function context] that is the first parameter
5126** to the xStep or xFinal callback routine that implements the aggregate
5127** function.
5129** This routine must be called from the same thread in which
5130** the aggregate SQL function is running.
5132SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
5135** CAPI3REF: User Data For Functions
5136** METHOD: sqlite3_context
5138** ^The sqlite3_user_data() interface returns a copy of
5139** the pointer that was the pUserData parameter (the 5th parameter)
5140** of the [sqlite3_create_function()]
5141** and [sqlite3_create_function16()] routines that originally
5142** registered the application defined function.
5144** This routine must be called from the same thread in which
5145** the application-defined function is running.
5147SQLITE_API void *sqlite3_user_data(sqlite3_context*);
5150** CAPI3REF: Database Connection For Functions
5151** METHOD: sqlite3_context
5153** ^The sqlite3_context_db_handle() interface returns a copy of
5154** the pointer to the [database connection] (the 1st parameter)
5155** of the [sqlite3_create_function()]
5156** and [sqlite3_create_function16()] routines that originally
5157** registered the application defined function.
5159SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
5162** CAPI3REF: Function Auxiliary Data
5163** METHOD: sqlite3_context
5165** These functions may be used by (non-aggregate) SQL functions to
5166** associate metadata with argument values. If the same value is passed to
5167** multiple invocations of the same SQL function during query execution, under
5168** some circumstances the associated metadata may be preserved. An example
5169** of where this might be useful is in a regular-expression matching
5170** function. The compiled version of the regular expression can be stored as
5171** metadata associated with the pattern string.
5172** Then as long as the pattern string remains the same,
5173** the compiled regular expression can be reused on multiple
5174** invocations of the same function.
5176** ^The sqlite3_get_auxdata(C,N) interface returns a pointer to the metadata
5177** associated by the sqlite3_set_auxdata(C,N,P,X) function with the Nth argument
5178** value to the application-defined function. ^N is zero for the left-most
5179** function argument. ^If there is no metadata
5180** associated with the function argument, the sqlite3_get_auxdata(C,N) interface
5181** returns a NULL pointer.
5183** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
5184** argument of the application-defined function. ^Subsequent
5185** calls to sqlite3_get_auxdata(C,N) return P from the most recent
5186** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
5187** NULL if the metadata has been discarded.
5188** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
5189** SQLite will invoke the destructor function X with parameter P exactly
5190** once, when the metadata is discarded.
5191** SQLite is free to discard the metadata at any time, including: <ul>
5192** <li> ^(when the corresponding function parameter changes)^, or
5193** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
5194** SQL statement)^, or
5195** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
5196** parameter)^, or
5197** <li> ^(during the original sqlite3_set_auxdata() call when a memory
5198** allocation error occurs.)^ </ul>
5200** Note the last bullet in particular. The destructor X in
5201** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
5202** sqlite3_set_auxdata() interface even returns. Hence sqlite3_set_auxdata()
5203** should be called near the end of the function implementation and the
5204** function implementation should not make any use of P after
5205** sqlite3_set_auxdata() has been called.
5207** ^(In practice, metadata is preserved between function calls for
5208** function parameters that are compile-time constants, including literal
5209** values and [parameters] and expressions composed from the same.)^
5211** The value of the N parameter to these interfaces should be non-negative.
5212** Future enhancements may make use of negative N values to define new
5213** kinds of function caching behavior.
5215** These routines must be called from the same thread in which
5216** the SQL function is running.
5218SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
5219SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
5223** CAPI3REF: Constants Defining Special Destructor Behavior
5225** These are special values for the destructor that is passed in as the
5226** final argument to routines like [sqlite3_result_blob()]. ^If the destructor
5227** argument is SQLITE_STATIC, it means that the content pointer is constant
5228** and will never change. It does not need to be destroyed. ^The
5229** SQLITE_TRANSIENT value means that the content will likely change in
5230** the near future and that SQLite should make its own private copy of
5231** the content before returning.
5233** The typedef is necessary to work around problems in certain
5234** C++ compilers.
5236typedef void (*sqlite3_destructor_type)(void*);
5237#define SQLITE_STATIC ((sqlite3_destructor_type)0)
5238#define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1)
5241** CAPI3REF: Setting The Result Of An SQL Function
5242** METHOD: sqlite3_context
5244** These routines are used by the xFunc or xFinal callbacks that
5245** implement SQL functions and aggregates. See
5246** [sqlite3_create_function()] and [sqlite3_create_function16()]
5247** for additional information.
5249** These functions work very much like the [parameter binding] family of
5250** functions used to bind values to host parameters in prepared statements.
5251** Refer to the [SQL parameter] documentation for additional information.
5253** ^The sqlite3_result_blob() interface sets the result from
5254** an application-defined function to be the BLOB whose content is pointed
5255** to by the second parameter and which is N bytes long where N is the
5256** third parameter.
5258** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
5259** interfaces set the result of the application-defined function to be
5260** a BLOB containing all zero bytes and N bytes in size.
5262** ^The sqlite3_result_double() interface sets the result from
5263** an application-defined function to be a floating point value specified
5264** by its 2nd argument.
5266** ^The sqlite3_result_error() and sqlite3_result_error16() functions
5267** cause the implemented SQL function to throw an exception.
5268** ^SQLite uses the string pointed to by the
5269** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
5270** as the text of an error message. ^SQLite interprets the error
5271** message string from sqlite3_result_error() as UTF-8. ^SQLite
5272** interprets the string from sqlite3_result_error16() as UTF-16 in native
5273** byte order. ^If the third parameter to sqlite3_result_error()
5274** or sqlite3_result_error16() is negative then SQLite takes as the error
5275** message all text up through the first zero character.
5276** ^If the third parameter to sqlite3_result_error() or
5277** sqlite3_result_error16() is non-negative then SQLite takes that many
5278** bytes (not characters) from the 2nd parameter as the error message.
5279** ^The sqlite3_result_error() and sqlite3_result_error16()
5280** routines make a private copy of the error message text before
5281** they return. Hence, the calling function can deallocate or
5282** modify the text after they return without harm.
5283** ^The sqlite3_result_error_code() function changes the error code
5284** returned by SQLite as a result of an error in a function. ^By default,
5285** the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error()
5286** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
5288** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
5289** error indicating that a string or BLOB is too long to represent.
5291** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
5292** error indicating that a memory allocation failed.
5294** ^The sqlite3_result_int() interface sets the return value
5295** of the application-defined function to be the 32-bit signed integer
5296** value given in the 2nd argument.
5297** ^The sqlite3_result_int64() interface sets the return value
5298** of the application-defined function to be the 64-bit signed integer
5299** value given in the 2nd argument.
5301** ^The sqlite3_result_null() interface sets the return value
5302** of the application-defined function to be NULL.
5304** ^The sqlite3_result_text(), sqlite3_result_text16(),
5305** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
5306** set the return value of the application-defined function to be
5307** a text string which is represented as UTF-8, UTF-16 native byte order,
5308** UTF-16 little endian, or UTF-16 big endian, respectively.
5309** ^The sqlite3_result_text64() interface sets the return value of an
5310** application-defined function to be a text string in an encoding
5311** specified by the fifth (and last) parameter, which must be one
5313** ^SQLite takes the text result from the application from
5314** the 2nd parameter of the sqlite3_result_text* interfaces.
5315** ^If the 3rd parameter to the sqlite3_result_text* interfaces
5316** is negative, then SQLite takes result text from the 2nd parameter
5317** through the first zero character.
5318** ^If the 3rd parameter to the sqlite3_result_text* interfaces
5319** is non-negative, then as many bytes (not characters) of the text
5320** pointed to by the 2nd parameter are taken as the application-defined
5321** function result. If the 3rd parameter is non-negative, then it
5322** must be the byte offset into the string where the NUL terminator would
5323** appear if the string where NUL terminated. If any NUL characters occur
5324** in the string at a byte offset that is less than the value of the 3rd
5325** parameter, then the resulting string will contain embedded NULs and the
5326** result of expressions operating on strings with embedded NULs is undefined.
5327** ^If the 4th parameter to the sqlite3_result_text* interfaces
5328** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
5329** function as the destructor on the text or BLOB result when it has
5330** finished using that result.
5331** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
5332** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
5333** assumes that the text or BLOB result is in constant space and does not
5334** copy the content of the parameter nor call a destructor on the content
5335** when it has finished using that result.
5336** ^If the 4th parameter to the sqlite3_result_text* interfaces
5337** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
5338** then SQLite makes a copy of the result into space obtained
5339** from [sqlite3_malloc()] before it returns.
5341** ^The sqlite3_result_value() interface sets the result of
5342** the application-defined function to be a copy of the
5343** [unprotected sqlite3_value] object specified by the 2nd parameter. ^The
5344** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
5345** so that the [sqlite3_value] specified in the parameter may change or
5346** be deallocated after sqlite3_result_value() returns without harm.
5347** ^A [protected sqlite3_value] object may always be used where an
5348** [unprotected sqlite3_value] object is required, so either
5349** kind of [sqlite3_value] object can be used with this interface.
5351** ^The sqlite3_result_pointer(C,P,T,D) interface sets the result to an
5352** SQL NULL value, just like [sqlite3_result_null(C)], except that it
5353** also associates the host-language pointer P or type T with that
5354** NULL value such that the pointer can be retrieved within an
5355** [application-defined SQL function] using [sqlite3_value_pointer()].
5356** ^If the D parameter is not NULL, then it is a pointer to a destructor
5357** for the P parameter. ^SQLite invokes D with P as its only argument
5358** when SQLite is finished with P. The T parameter should be a static
5359** string and preferably a string literal. The sqlite3_result_pointer()
5360** routine is part of the [pointer passing interface] added for SQLite 3.20.0.
5362** If these routines are called from within the different thread
5363** than the one containing the application-defined function that received
5364** the [sqlite3_context] pointer, the results are undefined.
5366SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
5367SQLITE_API void sqlite3_result_blob64(sqlite3_context*,const void*,
5368 sqlite3_uint64,void(*)(void*));
5369SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
5370SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
5371SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
5372SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
5373SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
5374SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
5375SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
5376SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
5377SQLITE_API void sqlite3_result_null(sqlite3_context*);
5378SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
5379SQLITE_API void sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
5380 void(*)(void*), unsigned char encoding);
5381SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
5382SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
5383SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
5384SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
5385SQLITE_API void sqlite3_result_pointer(sqlite3_context*, void*,const char*,void(*)(void*));
5386SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
5387SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
5391** CAPI3REF: Setting The Subtype Of An SQL Function
5392** METHOD: sqlite3_context
5394** The sqlite3_result_subtype(C,T) function causes the subtype of
5395** the result from the [application-defined SQL function] with
5396** [sqlite3_context] C to be the value T. Only the lower 8 bits
5397** of the subtype T are preserved in current versions of SQLite;
5398** higher order bits are discarded.
5399** The number of subtype bytes preserved by SQLite might increase
5400** in future releases of SQLite.
5402SQLITE_API void sqlite3_result_subtype(sqlite3_context*,unsigned int);
5405** CAPI3REF: Define New Collating Sequences
5406** METHOD: sqlite3
5408** ^These functions add, remove, or modify a [collation] associated
5409** with the [database connection] specified as the first argument.
5411** ^The name of the collation is a UTF-8 string
5412** for sqlite3_create_collation() and sqlite3_create_collation_v2()
5413** and a UTF-16 string in native byte order for sqlite3_create_collation16().
5414** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
5415** considered to be the same name.
5417** ^(The third argument (eTextRep) must be one of the constants:
5418** <ul>
5419** <li> [SQLITE_UTF8],
5420** <li> [SQLITE_UTF16LE],
5421** <li> [SQLITE_UTF16BE],
5422** <li> [SQLITE_UTF16], or
5423** <li> [SQLITE_UTF16_ALIGNED].
5424** </ul>)^
5425** ^The eTextRep argument determines the encoding of strings passed
5426** to the collating function callback, xCallback.
5427** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
5428** force strings to be UTF16 with native byte order.
5429** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
5430** on an even byte address.
5432** ^The fourth argument, pArg, is an application data pointer that is passed
5433** through as the first argument to the collating function callback.
5435** ^The fifth argument, xCallback, is a pointer to the collating function.
5436** ^Multiple collating functions can be registered using the same name but
5437** with different eTextRep parameters and SQLite will use whichever
5438** function requires the least amount of data transformation.
5439** ^If the xCallback argument is NULL then the collating function is
5440** deleted. ^When all collating functions having the same name are deleted,
5441** that collation is no longer usable.
5443** ^The collating function callback is invoked with a copy of the pArg
5444** application data pointer and with two strings in the encoding specified
5445** by the eTextRep argument. The collating function must return an
5446** integer that is negative, zero, or positive
5447** if the first string is less than, equal to, or greater than the second,
5448** respectively. A collating function must always return the same answer
5449** given the same inputs. If two or more collating functions are registered
5450** to the same collation name (using different eTextRep values) then all
5451** must give an equivalent answer when invoked with equivalent strings.
5452** The collating function must obey the following properties for all
5453** strings A, B, and C:
5455** <ol>
5456** <li> If A==B then B==A.
5457** <li> If A==B and B==C then A==C.
5458** <li> If A&lt;B THEN B&gt;A.
5459** <li> If A&lt;B and B&lt;C then A&lt;C.
5460** </ol>
5462** If a collating function fails any of the above constraints and that
5463** collating function is registered and used, then the behavior of SQLite
5464** is undefined.
5466** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
5467** with the addition that the xDestroy callback is invoked on pArg when
5468** the collating function is deleted.
5469** ^Collating functions are deleted when they are overridden by later
5470** calls to the collation creation functions or when the
5471** [database connection] is closed using [sqlite3_close()].
5473** ^The xDestroy callback is <u>not</u> called if the
5474** sqlite3_create_collation_v2() function fails. Applications that invoke
5475** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should
5476** check the return code and dispose of the application data pointer
5477** themselves rather than expecting SQLite to deal with it for them.
5478** This is different from every other SQLite interface. The inconsistency
5479** is unfortunate but cannot be changed without breaking backwards
5480** compatibility.
5482** See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
5484SQLITE_API int sqlite3_create_collation(
5485 sqlite3*,
5486 const char *zName,
5487 int eTextRep,
5488 void *pArg,
5489 int(*xCompare)(void*,int,const void*,int,const void*)
5491SQLITE_API int sqlite3_create_collation_v2(
5492 sqlite3*,
5493 const char *zName,
5494 int eTextRep,
5495 void *pArg,
5496 int(*xCompare)(void*,int,const void*,int,const void*),
5497 void(*xDestroy)(void*)
5499SQLITE_API int sqlite3_create_collation16(
5500 sqlite3*,
5501 const void *zName,
5502 int eTextRep,
5503 void *pArg,
5504 int(*xCompare)(void*,int,const void*,int,const void*)
5508** CAPI3REF: Collation Needed Callbacks
5509** METHOD: sqlite3
5511** ^To avoid having to register all collation sequences before a database
5512** can be used, a single callback function may be registered with the
5513** [database connection] to be invoked whenever an undefined collation
5514** sequence is required.
5516** ^If the function is registered using the sqlite3_collation_needed() API,
5517** then it is passed the names of undefined collation sequences as strings
5518** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
5519** the names are passed as UTF-16 in machine native byte order.
5520** ^A call to either function replaces the existing collation-needed callback.
5522** ^(When the callback is invoked, the first argument passed is a copy
5523** of the second argument to sqlite3_collation_needed() or
5524** sqlite3_collation_needed16(). The second argument is the database
5525** connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
5526** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
5527** sequence function required. The fourth parameter is the name of the
5528** required collation sequence.)^
5530** The callback function should register the desired collation using
5531** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
5532** [sqlite3_create_collation_v2()].
5534SQLITE_API int sqlite3_collation_needed(
5535 sqlite3*,
5536 void*,
5537 void(*)(void*,sqlite3*,int eTextRep,const char*)
5539SQLITE_API int sqlite3_collation_needed16(
5540 sqlite3*,
5541 void*,
5542 void(*)(void*,sqlite3*,int eTextRep,const void*)
5547** Specify the key for an encrypted database. This routine should be
5548** called right after sqlite3_open().
5550** The code to implement this API is not available in the public release
5551** of SQLite.
5553SQLITE_API int sqlite3_key(
5554 sqlite3 *db, /* Database to be rekeyed */
5555 const void *pKey, int nKey /* The key */
5557SQLITE_API int sqlite3_key_v2(
5558 sqlite3 *db, /* Database to be rekeyed */
5559 const char *zDbName, /* Name of the database */
5560 const void *pKey, int nKey /* The key */
5564** Change the key on an open database. If the current database is not
5565** encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the
5566** database is decrypted.
5568** The code to implement this API is not available in the public release
5569** of SQLite.
5571SQLITE_API int sqlite3_rekey(
5572 sqlite3 *db, /* Database to be rekeyed */
5573 const void *pKey, int nKey /* The new key */
5575SQLITE_API int sqlite3_rekey_v2(
5576 sqlite3 *db, /* Database to be rekeyed */
5577 const char *zDbName, /* Name of the database */
5578 const void *pKey, int nKey /* The new key */
5582** Specify the activation key for a SEE database. Unless
5583** activated, none of the SEE routines will work.
5585SQLITE_API void sqlite3_activate_see(
5586 const char *zPassPhrase /* Activation phrase */
5592** Specify the activation key for a CEROD database. Unless
5593** activated, none of the CEROD routines will work.
5595SQLITE_API void sqlite3_activate_cerod(
5596 const char *zPassPhrase /* Activation phrase */
5601** CAPI3REF: Suspend Execution For A Short Time
5603** The sqlite3_sleep() function causes the current thread to suspend execution
5604** for at least a number of milliseconds specified in its parameter.
5606** If the operating system does not support sleep requests with
5607** millisecond time resolution, then the time will be rounded up to
5608** the nearest second. The number of milliseconds of sleep actually
5609** requested from the operating system is returned.
5611** ^SQLite implements this interface by calling the xSleep()
5612** method of the default [sqlite3_vfs] object. If the xSleep() method
5613** of the default VFS is not implemented correctly, or not implemented at
5614** all, then the behavior of sqlite3_sleep() may deviate from the description
5615** in the previous paragraphs.
5617SQLITE_API int sqlite3_sleep(int);
5620** CAPI3REF: Name Of The Folder Holding Temporary Files
5622** ^(If this global variable is made to point to a string which is
5623** the name of a folder (a.k.a. directory), then all temporary files
5624** created by SQLite when using a built-in [sqlite3_vfs | VFS]
5625** will be placed in that directory.)^ ^If this variable
5626** is a NULL pointer, then SQLite performs a search for an appropriate
5627** temporary file directory.
5629** Applications are strongly discouraged from using this global variable.
5630** It is required to set a temporary folder on Windows Runtime (WinRT).
5631** But for all other platforms, it is highly recommended that applications
5632** neither read nor write this variable. This global variable is a relic
5633** that exists for backwards compatibility of legacy applications and should
5634** be avoided in new projects.
5636** It is not safe to read or modify this variable in more than one
5637** thread at a time. It is not safe to read or modify this variable
5638** if a [database connection] is being used at the same time in a separate
5639** thread.
5640** It is intended that this variable be set once
5641** as part of process initialization and before any SQLite interface
5642** routines have been called and that this variable remain unchanged
5643** thereafter.
5645** ^The [temp_store_directory pragma] may modify this variable and cause
5646** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,
5647** the [temp_store_directory pragma] always assumes that any string
5648** that this variable points to is held in memory obtained from
5649** [sqlite3_malloc] and the pragma may attempt to free that memory
5650** using [sqlite3_free].
5651** Hence, if this variable is modified directly, either it should be
5652** made NULL or made to point to memory obtained from [sqlite3_malloc]
5653** or else the use of the [temp_store_directory pragma] should be avoided.
5654** Except when requested by the [temp_store_directory pragma], SQLite
5655** does not free the memory that sqlite3_temp_directory points to. If
5656** the application wants that memory to be freed, it must do
5657** so itself, taking care to only do so after all [database connection]
5658** objects have been destroyed.
5660** <b>Note to Windows Runtime users:</b> The temporary directory must be set
5661** prior to calling [sqlite3_open] or [sqlite3_open_v2]. Otherwise, various
5662** features that require the use of temporary files may fail. Here is an
5663** example of how to do this using C++ with the Windows Runtime:
5665** <blockquote><pre>
5666** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
5667** &nbsp; TemporaryFolder->Path->Data();
5668** char zPathBuf&#91;MAX_PATH + 1&#93;;
5669** memset(zPathBuf, 0, sizeof(zPathBuf));
5670** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
5671** &nbsp; NULL, NULL);
5672** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
5673** </pre></blockquote>
5675SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
5678** CAPI3REF: Name Of The Folder Holding Database Files
5680** ^(If this global variable is made to point to a string which is
5681** the name of a folder (a.k.a. directory), then all database files
5682** specified with a relative pathname and created or accessed by
5683** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
5684** to be relative to that directory.)^ ^If this variable is a NULL
5685** pointer, then SQLite assumes that all database files specified
5686** with a relative pathname are relative to the current directory
5687** for the process. Only the windows VFS makes use of this global
5688** variable; it is ignored by the unix VFS.
5690** Changing the value of this variable while a database connection is
5691** open can result in a corrupt database.
5693** It is not safe to read or modify this variable in more than one
5694** thread at a time. It is not safe to read or modify this variable
5695** if a [database connection] is being used at the same time in a separate
5696** thread.
5697** It is intended that this variable be set once
5698** as part of process initialization and before any SQLite interface
5699** routines have been called and that this variable remain unchanged
5700** thereafter.
5702** ^The [data_store_directory pragma] may modify this variable and cause
5703** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,
5704** the [data_store_directory pragma] always assumes that any string
5705** that this variable points to is held in memory obtained from
5706** [sqlite3_malloc] and the pragma may attempt to free that memory
5707** using [sqlite3_free].
5708** Hence, if this variable is modified directly, either it should be
5709** made NULL or made to point to memory obtained from [sqlite3_malloc]
5710** or else the use of the [data_store_directory pragma] should be avoided.
5712SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
5715** CAPI3REF: Win32 Specific Interface
5717** These interfaces are available only on Windows. The
5718** [sqlite3_win32_set_directory] interface is used to set the value associated
5719** with the [sqlite3_temp_directory] or [sqlite3_data_directory] variable, to
5720** zValue, depending on the value of the type parameter. The zValue parameter
5721** should be NULL to cause the previous value to be freed via [sqlite3_free];
5722** a non-NULL value will be copied into memory obtained from [sqlite3_malloc]
5723** prior to being used. The [sqlite3_win32_set_directory] interface returns
5724** [SQLITE_OK] to indicate success, [SQLITE_ERROR] if the type is unsupported,
5725** or [SQLITE_NOMEM] if memory could not be allocated. The value of the
5726** [sqlite3_data_directory] variable is intended to act as a replacement for
5727** the current directory on the sub-platforms of Win32 where that concept is
5728** not present, e.g. WinRT and UWP. The [sqlite3_win32_set_directory8] and
5729** [sqlite3_win32_set_directory16] interfaces behave exactly the same as the
5730** sqlite3_win32_set_directory interface except the string parameter must be
5731** UTF-8 or UTF-16, respectively.
5733SQLITE_API int sqlite3_win32_set_directory(
5734 unsigned long type, /* Identifier for directory being set or reset */
5735 void *zValue /* New value for directory being set or reset */
5737SQLITE_API int sqlite3_win32_set_directory8(unsigned long type, const char *zValue);
5738SQLITE_API int sqlite3_win32_set_directory16(unsigned long type, const void *zValue);
5741** CAPI3REF: Win32 Directory Types
5743** These macros are only available on Windows. They define the allowed values
5744** for the type argument to the [sqlite3_win32_set_directory] interface.
5750** CAPI3REF: Test For Auto-Commit Mode
5751** KEYWORDS: {autocommit mode}
5752** METHOD: sqlite3
5754** ^The sqlite3_get_autocommit() interface returns non-zero or
5755** zero if the given database connection is or is not in autocommit mode,
5756** respectively. ^Autocommit mode is on by default.
5757** ^Autocommit mode is disabled by a [BEGIN] statement.
5758** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
5760** If certain kinds of errors occur on a statement within a multi-statement
5761** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
5763** transaction might be rolled back automatically. The only way to
5764** find out whether SQLite automatically rolled back the transaction after
5765** an error is to use this function.
5767** If another thread changes the autocommit status of the database
5768** connection while this routine is running, then the return value
5769** is undefined.
5771SQLITE_API int sqlite3_get_autocommit(sqlite3*);
5774** CAPI3REF: Find The Database Handle Of A Prepared Statement
5775** METHOD: sqlite3_stmt
5777** ^The sqlite3_db_handle interface returns the [database connection] handle
5778** to which a [prepared statement] belongs. ^The [database connection]
5779** returned by sqlite3_db_handle is the same [database connection]
5780** that was the first argument
5781** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
5782** create the statement in the first place.
5784SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
5787** CAPI3REF: Return The Filename For A Database Connection
5788** METHOD: sqlite3
5790** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
5791** associated with database N of connection D. ^The main database file
5792** has the name "main". If there is no attached database N on the database
5793** connection D, or if database N is a temporary or in-memory database, then
5794** a NULL pointer is returned.
5796** ^The filename returned by this function is the output of the
5797** xFullPathname method of the [VFS]. ^In other words, the filename
5798** will be an absolute pathname, even if the filename used
5799** to open the database originally was a URI or relative pathname.
5801SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
5804** CAPI3REF: Determine if a database is read-only
5805** METHOD: sqlite3
5807** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
5808** of connection D is read-only, 0 if it is read/write, or -1 if N is not
5809** the name of a database on connection D.
5811SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
5814** CAPI3REF: Find the next prepared statement
5815** METHOD: sqlite3
5817** ^This interface returns a pointer to the next [prepared statement] after
5818** pStmt associated with the [database connection] pDb. ^If pStmt is NULL
5819** then this interface returns a pointer to the first prepared statement
5820** associated with the database connection pDb. ^If no prepared statement
5821** satisfies the conditions of this routine, it returns NULL.
5823** The [database connection] pointer D in a call to
5824** [sqlite3_next_stmt(D,S)] must refer to an open database
5825** connection and in particular must not be a NULL pointer.
5827SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
5830** CAPI3REF: Commit And Rollback Notification Callbacks
5831** METHOD: sqlite3
5833** ^The sqlite3_commit_hook() interface registers a callback
5834** function to be invoked whenever a transaction is [COMMIT | committed].
5835** ^Any callback set by a previous call to sqlite3_commit_hook()
5836** for the same database connection is overridden.
5837** ^The sqlite3_rollback_hook() interface registers a callback
5838** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
5839** ^Any callback set by a previous call to sqlite3_rollback_hook()
5840** for the same database connection is overridden.
5841** ^The pArg argument is passed through to the callback.
5842** ^If the callback on a commit hook function returns non-zero,
5843** then the commit is converted into a rollback.
5845** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
5846** return the P argument from the previous call of the same function
5847** on the same [database connection] D, or NULL for
5848** the first call for each function on D.
5850** The commit and rollback hook callbacks are not reentrant.
5851** The callback implementation must not do anything that will modify
5852** the database connection that invoked the callback. Any actions
5853** to modify the database connection must be deferred until after the
5854** completion of the [sqlite3_step()] call that triggered the commit
5855** or rollback hook in the first place.
5856** Note that running any other SQL statements, including SELECT statements,
5857** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
5858** the database connections for the meaning of "modify" in this paragraph.
5860** ^Registering a NULL function disables the callback.
5862** ^When the commit hook callback routine returns zero, the [COMMIT]
5863** operation is allowed to continue normally. ^If the commit hook
5864** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
5865** ^The rollback hook is invoked on a rollback that results from a commit
5866** hook returning non-zero, just as it would be with any other rollback.
5868** ^For the purposes of this API, a transaction is said to have been
5869** rolled back if an explicit "ROLLBACK" statement is executed, or
5870** an error or constraint causes an implicit rollback to occur.
5871** ^The rollback callback is not invoked if a transaction is
5872** automatically rolled back because the database connection is closed.
5874** See also the [sqlite3_update_hook()] interface.
5876SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
5877SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
5880** CAPI3REF: Data Change Notification Callbacks
5881** METHOD: sqlite3
5883** ^The sqlite3_update_hook() interface registers a callback function
5884** with the [database connection] identified by the first argument
5885** to be invoked whenever a row is updated, inserted or deleted in
5886** a [rowid table].
5887** ^Any callback set by a previous call to this function
5888** for the same database connection is overridden.
5890** ^The second argument is a pointer to the function to invoke when a
5891** row is updated, inserted or deleted in a rowid table.
5892** ^The first argument to the callback is a copy of the third argument
5893** to sqlite3_update_hook().
5894** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
5895** or [SQLITE_UPDATE], depending on the operation that caused the callback
5896** to be invoked.
5897** ^The third and fourth arguments to the callback contain pointers to the
5898** database and table name containing the affected row.
5899** ^The final callback parameter is the [rowid] of the row.
5900** ^In the case of an update, this is the [rowid] after the update takes place.
5902** ^(The update hook is not invoked when internal system tables are
5903** modified (i.e. sqlite_master and sqlite_sequence).)^
5904** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
5906** ^In the current implementation, the update hook
5907** is not invoked when conflicting rows are deleted because of an
5908** [ON CONFLICT | ON CONFLICT REPLACE] clause. ^Nor is the update hook
5909** invoked when rows are deleted using the [truncate optimization].
5910** The exceptions defined in this paragraph might change in a future
5911** release of SQLite.
5913** The update hook implementation must not do anything that will modify
5914** the database connection that invoked the update hook. Any actions
5915** to modify the database connection must be deferred until after the
5916** completion of the [sqlite3_step()] call that triggered the update hook.
5917** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
5918** database connections for the meaning of "modify" in this paragraph.
5920** ^The sqlite3_update_hook(D,C,P) function
5921** returns the P argument from the previous call
5922** on the same [database connection] D, or NULL for
5923** the first call on D.
5925** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
5926** and [sqlite3_preupdate_hook()] interfaces.
5928SQLITE_API void *sqlite3_update_hook(
5929 sqlite3*,
5930 void(*)(void *,int ,char const *,char const *,sqlite3_int64),
5931 void*
5935** CAPI3REF: Enable Or Disable Shared Pager Cache
5937** ^(This routine enables or disables the sharing of the database cache
5938** and schema data structures between [database connection | connections]
5939** to the same database. Sharing is enabled if the argument is true
5940** and disabled if the argument is false.)^
5942** ^Cache sharing is enabled and disabled for an entire process.
5943** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]).
5944** In prior versions of SQLite,
5945** sharing was enabled or disabled for each thread separately.
5947** ^(The cache sharing mode set by this interface effects all subsequent
5948** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
5949** Existing database connections continue use the sharing mode
5950** that was in effect at the time they were opened.)^
5952** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
5953** successfully. An [error code] is returned otherwise.)^
5955** ^Shared cache is disabled by default. But this might change in
5956** future releases of SQLite. Applications that care about shared
5957** cache setting should set it explicitly.
5959** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
5960** and will always return SQLITE_MISUSE. On those systems,
5961** shared cache mode should be enabled per-database connection via
5962** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
5964** This interface is threadsafe on processors where writing a
5965** 32-bit integer is atomic.
5967** See Also: [SQLite Shared-Cache Mode]
5969SQLITE_API int sqlite3_enable_shared_cache(int);
5972** CAPI3REF: Attempt To Free Heap Memory
5974** ^The sqlite3_release_memory() interface attempts to free N bytes
5975** of heap memory by deallocating non-essential memory allocations
5976** held by the database library. Memory used to cache database
5977** pages to improve performance is an example of non-essential memory.
5978** ^sqlite3_release_memory() returns the number of bytes actually freed,
5979** which might be more or less than the amount requested.
5980** ^The sqlite3_release_memory() routine is a no-op returning zero
5981** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
5983** See also: [sqlite3_db_release_memory()]
5985SQLITE_API int sqlite3_release_memory(int);
5988** CAPI3REF: Free Memory Used By A Database Connection
5989** METHOD: sqlite3
5991** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
5992** memory as possible from database connection D. Unlike the
5993** [sqlite3_release_memory()] interface, this interface is in effect even
5994** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
5995** omitted.
5997** See also: [sqlite3_release_memory()]
5999SQLITE_API int sqlite3_db_release_memory(sqlite3*);
6002** CAPI3REF: Impose A Limit On Heap Size
6004** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
6005** soft limit on the amount of heap memory that may be allocated by SQLite.
6006** ^SQLite strives to keep heap memory utilization below the soft heap
6007** limit by reducing the number of pages held in the page cache
6008** as heap memory usages approaches the limit.
6009** ^The soft heap limit is "soft" because even though SQLite strives to stay
6010** below the limit, it will exceed the limit rather than generate
6011** an [SQLITE_NOMEM] error. In other words, the soft heap limit
6012** is advisory only.
6014** ^The return value from sqlite3_soft_heap_limit64() is the size of
6015** the soft heap limit prior to the call, or negative in the case of an
6016** error. ^If the argument N is negative
6017** then no change is made to the soft heap limit. Hence, the current
6018** size of the soft heap limit can be determined by invoking
6019** sqlite3_soft_heap_limit64() with a negative argument.
6021** ^If the argument N is zero then the soft heap limit is disabled.
6023** ^(The soft heap limit is not enforced in the current implementation
6024** if one or more of following conditions are true:
6026** <ul>
6027** <li> The soft heap limit is set to zero.
6028** <li> Memory accounting is disabled using a combination of the
6029** [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
6030** the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
6031** <li> An alternative page cache implementation is specified using
6032** [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
6033** <li> The page cache allocates from its own memory pool supplied
6034** by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
6035** from the heap.
6036** </ul>)^
6038** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]),
6039** the soft heap limit is enforced
6040** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
6041** compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
6042** the soft heap limit is enforced on every memory allocation. Without
6043** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
6044** when memory is allocated by the page cache. Testing suggests that because
6045** the page cache is the predominate memory user in SQLite, most
6046** applications will achieve adequate soft heap limit enforcement without
6049** The circumstances under which SQLite will enforce the soft heap limit may
6050** changes in future releases of SQLite.
6052SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
6055** CAPI3REF: Deprecated Soft Heap Limit Interface
6058** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
6059** interface. This routine is provided for historical compatibility
6060** only. All new applications should use the
6061** [sqlite3_soft_heap_limit64()] interface rather than this one.
6063SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
6067** CAPI3REF: Extract Metadata About A Column Of A Table
6068** METHOD: sqlite3
6070** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
6071** information about column C of table T in database D
6072** on [database connection] X.)^ ^The sqlite3_table_column_metadata()
6073** interface returns SQLITE_OK and fills in the non-NULL pointers in
6074** the final five arguments with appropriate values if the specified
6075** column exists. ^The sqlite3_table_column_metadata() interface returns
6076** SQLITE_ERROR and if the specified column does not exist.
6077** ^If the column-name parameter to sqlite3_table_column_metadata() is a
6078** NULL pointer, then this routine simply checks for the existence of the
6079** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
6080** does not. If the table name parameter T in a call to
6081** sqlite3_table_column_metadata(X,D,T,C,...) is NULL then the result is
6082** undefined behavior.
6084** ^The column is identified by the second, third and fourth parameters to
6085** this function. ^(The second parameter is either the name of the database
6086** (i.e. "main", "temp", or an attached database) containing the specified
6087** table or NULL.)^ ^If it is NULL, then all attached databases are searched
6088** for the table using the same algorithm used by the database engine to
6089** resolve unqualified table references.
6091** ^The third and fourth parameters to this function are the table and column
6092** name of the desired column, respectively.
6094** ^Metadata is returned by writing to the memory locations passed as the 5th
6095** and subsequent parameters to this function. ^Any of these arguments may be
6096** NULL, in which case the corresponding element of metadata is omitted.
6098** ^(<blockquote>
6099** <table border="1">
6100** <tr><th> Parameter <th> Output<br>Type <th> Description
6102** <tr><td> 5th <td> const char* <td> Data type
6103** <tr><td> 6th <td> const char* <td> Name of default collation sequence
6104** <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint
6105** <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY
6106** <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT]
6107** </table>
6108** </blockquote>)^
6110** ^The memory pointed to by the character pointers returned for the
6111** declaration type and collation sequence is valid until the next
6112** call to any SQLite API function.
6114** ^If the specified table is actually a view, an [error code] is returned.
6116** ^If the specified column is "rowid", "oid" or "_rowid_" and the table
6117** is not a [WITHOUT ROWID] table and an
6118** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
6119** parameters are set for the explicitly declared column. ^(If there is no
6120** [INTEGER PRIMARY KEY] column, then the outputs
6121** for the [rowid] are set as follows:
6123** <pre>
6124** data type: "INTEGER"
6125** collation sequence: "BINARY"
6126** not null: 0
6127** primary key: 1
6128** auto increment: 0
6129** </pre>)^
6131** ^This function causes all database schemas to be read from disk and
6132** parsed, if that has not already been done, and returns an error if
6133** any errors are encountered while loading the schema.
6135SQLITE_API int sqlite3_table_column_metadata(
6136 sqlite3 *db, /* Connection handle */
6137 const char *zDbName, /* Database name or NULL */
6138 const char *zTableName, /* Table name */
6139 const char *zColumnName, /* Column name */
6140 char const **pzDataType, /* OUTPUT: Declared data type */
6141 char const **pzCollSeq, /* OUTPUT: Collation sequence name */
6142 int *pNotNull, /* OUTPUT: True if NOT NULL constraint exists */
6143 int *pPrimaryKey, /* OUTPUT: True if column part of PK */
6144 int *pAutoinc /* OUTPUT: True if column is auto-increment */
6148** CAPI3REF: Load An Extension
6149** METHOD: sqlite3
6151** ^This interface loads an SQLite extension library from the named file.
6153** ^The sqlite3_load_extension() interface attempts to load an
6154** [SQLite extension] library contained in the file zFile. If
6155** the file cannot be loaded directly, attempts are made to load
6156** with various operating-system specific extensions added.
6157** So for example, if "samplelib" cannot be loaded, then names like
6158** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
6159** be tried also.
6161** ^The entry point is zProc.
6162** ^(zProc may be 0, in which case SQLite will try to come up with an
6163** entry point name on its own. It first tries "sqlite3_extension_init".
6164** If that does not work, it constructs a name "sqlite3_X_init" where the
6165** X is consists of the lower-case equivalent of all ASCII alphabetic
6166** characters in the filename from the last "/" to the first following
6167** "." and omitting any initial "lib".)^
6168** ^The sqlite3_load_extension() interface returns
6169** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
6170** ^If an error occurs and pzErrMsg is not 0, then the
6171** [sqlite3_load_extension()] interface shall attempt to
6172** fill *pzErrMsg with error message text stored in memory
6173** obtained from [sqlite3_malloc()]. The calling function
6174** should free this memory by calling [sqlite3_free()].
6176** ^Extension loading must be enabled using
6177** [sqlite3_enable_load_extension()] or
6178** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
6179** prior to calling this API,
6180** otherwise an error will be returned.
6182** <b>Security warning:</b> It is recommended that the
6183** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
6184** interface. The use of the [sqlite3_enable_load_extension()] interface
6185** should be avoided. This will keep the SQL function [load_extension()]
6186** disabled and prevent SQL injections from giving attackers
6187** access to extension loading capabilities.
6189** See also the [load_extension() SQL function].
6191SQLITE_API int sqlite3_load_extension(
6192 sqlite3 *db, /* Load the extension into this database connection */
6193 const char *zFile, /* Name of the shared library containing extension */
6194 const char *zProc, /* Entry point. Derived from zFile if 0 */
6195 char **pzErrMsg /* Put error message here if not 0 */
6199** CAPI3REF: Enable Or Disable Extension Loading
6200** METHOD: sqlite3
6202** ^So as not to open security holes in older applications that are
6203** unprepared to deal with [extension loading], and as a means of disabling
6204** [extension loading] while evaluating user-entered SQL, the following API
6205** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
6207** ^Extension loading is off by default.
6208** ^Call the sqlite3_enable_load_extension() routine with onoff==1
6209** to turn extension loading on and call it with onoff==0 to turn
6210** it back off again.
6212** ^This interface enables or disables both the C-API
6213** [sqlite3_load_extension()] and the SQL function [load_extension()].
6214** ^(Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
6215** to enable or disable only the C-API.)^
6217** <b>Security warning:</b> It is recommended that extension loading
6218** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
6219** rather than this interface, so the [load_extension()] SQL function
6220** remains disabled. This will prevent SQL injections from giving attackers
6221** access to extension loading capabilities.
6223SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
6226** CAPI3REF: Automatically Load Statically Linked Extensions
6228** ^This interface causes the xEntryPoint() function to be invoked for
6229** each new [database connection] that is created. The idea here is that
6230** xEntryPoint() is the entry point for a statically linked [SQLite extension]
6231** that is to be automatically loaded into all new database connections.
6233** ^(Even though the function prototype shows that xEntryPoint() takes
6234** no arguments and returns void, SQLite invokes xEntryPoint() with three
6235** arguments and expects an integer result as if the signature of the
6236** entry point where as follows:
6238** <blockquote><pre>
6239** &nbsp; int xEntryPoint(
6240** &nbsp; sqlite3 *db,
6241** &nbsp; const char **pzErrMsg,
6242** &nbsp; const struct sqlite3_api_routines *pThunk
6243** &nbsp; );
6244** </pre></blockquote>)^
6246** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
6247** point to an appropriate error message (obtained from [sqlite3_mprintf()])
6248** and return an appropriate [error code]. ^SQLite ensures that *pzErrMsg
6249** is NULL before calling the xEntryPoint(). ^SQLite will invoke
6250** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns. ^If any
6251** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
6252** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
6254** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
6255** on the list of automatic extensions is a harmless no-op. ^No entry point
6256** will be called more than once for each database connection that is opened.
6258** See also: [sqlite3_reset_auto_extension()]
6259** and [sqlite3_cancel_auto_extension()]
6261SQLITE_API int sqlite3_auto_extension(void(*xEntryPoint)(void));
6264** CAPI3REF: Cancel Automatic Extension Loading
6266** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
6267** initialization routine X that was registered using a prior call to
6268** [sqlite3_auto_extension(X)]. ^The [sqlite3_cancel_auto_extension(X)]
6269** routine returns 1 if initialization routine X was successfully
6270** unregistered and it returns 0 if X was not on the list of initialization
6271** routines.
6273SQLITE_API int sqlite3_cancel_auto_extension(void(*xEntryPoint)(void));
6276** CAPI3REF: Reset Automatic Extension Loading
6278** ^This interface disables all automatic extensions previously
6279** registered using [sqlite3_auto_extension()].
6281SQLITE_API void sqlite3_reset_auto_extension(void);
6284** The interface to the virtual-table mechanism is currently considered
6285** to be experimental. The interface might change in incompatible ways.
6286** If this is a problem for you, do not use the interface at this time.
6288** When the virtual-table mechanism stabilizes, we will declare the
6289** interface fixed, support it indefinitely, and remove this comment.
6293** Structures used by the virtual table interface
6295typedef struct sqlite3_vtab sqlite3_vtab;
6296typedef struct sqlite3_index_info sqlite3_index_info;
6297typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
6298typedef struct sqlite3_module sqlite3_module;
6301** CAPI3REF: Virtual Table Object
6302** KEYWORDS: sqlite3_module {virtual table module}
6304** This structure, sometimes called a "virtual table module",
6305** defines the implementation of a [virtual tables].
6306** This structure consists mostly of methods for the module.
6308** ^A virtual table module is created by filling in a persistent
6309** instance of this structure and passing a pointer to that instance
6310** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
6311** ^The registration remains valid until it is replaced by a different
6312** module or until the [database connection] closes. The content
6313** of this structure must not change while it is registered with
6314** any database connection.
6316struct sqlite3_module {
6317 int iVersion;
6318 int (*xCreate)(sqlite3*, void *pAux,
6319 int argc, const char *const*argv,
6320 sqlite3_vtab **ppVTab, char**);
6321 int (*xConnect)(sqlite3*, void *pAux,
6322 int argc, const char *const*argv,
6323 sqlite3_vtab **ppVTab, char**);
6324 int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
6325 int (*xDisconnect)(sqlite3_vtab *pVTab);
6326 int (*xDestroy)(sqlite3_vtab *pVTab);
6327 int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
6328 int (*xClose)(sqlite3_vtab_cursor*);
6329 int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
6330 int argc, sqlite3_value **argv);
6331 int (*xNext)(sqlite3_vtab_cursor*);
6332 int (*xEof)(sqlite3_vtab_cursor*);
6333 int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
6334 int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
6335 int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
6336 int (*xBegin)(sqlite3_vtab *pVTab);
6337 int (*xSync)(sqlite3_vtab *pVTab);
6338 int (*xCommit)(sqlite3_vtab *pVTab);
6339 int (*xRollback)(sqlite3_vtab *pVTab);
6340 int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
6341 void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
6342 void **ppArg);
6343 int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
6344 /* The methods above are in version 1 of the sqlite_module object. Those
6345 ** below are for version 2 and greater. */
6346 int (*xSavepoint)(sqlite3_vtab *pVTab, int);
6347 int (*xRelease)(sqlite3_vtab *pVTab, int);
6348 int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
6349 /* The methods above are in versions 1 and 2 of the sqlite_module object.
6350 ** Those below are for version 3 and greater. */
6351 int (*xShadowName)(const char*);
6355** CAPI3REF: Virtual Table Indexing Information
6356** KEYWORDS: sqlite3_index_info
6358** The sqlite3_index_info structure and its substructures is used as part
6359** of the [virtual table] interface to
6360** pass information into and receive the reply from the [xBestIndex]
6361** method of a [virtual table module]. The fields under **Inputs** are the
6362** inputs to xBestIndex and are read-only. xBestIndex inserts its
6363** results into the **Outputs** fields.
6365** ^(The aConstraint[] array records WHERE clause constraints of the form:
6367** <blockquote>column OP expr</blockquote>
6369** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^ ^(The particular operator is
6370** stored in aConstraint[].op using one of the
6372** ^(The index of the column is stored in
6373** aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the
6374** expr on the right-hand side can be evaluated (and thus the constraint
6375** is usable) and false if it cannot.)^
6377** ^The optimizer automatically inverts terms of the form "expr OP column"
6378** and makes other simplifications to the WHERE clause in an attempt to
6379** get as many WHERE clause terms into the form shown above as possible.
6380** ^The aConstraint[] array only reports WHERE clause terms that are
6381** relevant to the particular virtual table being queried.
6383** ^Information about the ORDER BY clause is stored in aOrderBy[].
6384** ^Each term of aOrderBy records a column of the ORDER BY clause.
6386** The colUsed field indicates which columns of the virtual table may be
6387** required by the current scan. Virtual table columns are numbered from
6388** zero in the order in which they appear within the CREATE TABLE statement
6389** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),
6390** the corresponding bit is set within the colUsed mask if the column may be
6391** required by SQLite. If the table has at least 64 columns and any column
6392** to the right of the first 63 is required, then bit 63 of colUsed is also
6393** set. In other words, column iCol may be required if the expression
6394** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to
6395** non-zero.
6397** The [xBestIndex] method must fill aConstraintUsage[] with information
6398** about what parameters to pass to xFilter. ^If argvIndex>0 then
6399** the right-hand side of the corresponding aConstraint[] is evaluated
6400** and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit
6401** is true, then the constraint is assumed to be fully handled by the
6402** virtual table and is not checked again by SQLite.)^
6404** ^The idxNum and idxPtr values are recorded and passed into the
6405** [xFilter] method.
6406** ^[sqlite3_free()] is used to free idxPtr if and only if
6407** needToFreeIdxPtr is true.
6409** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
6410** the correct order to satisfy the ORDER BY clause so that no separate
6411** sorting step is required.
6413** ^The estimatedCost value is an estimate of the cost of a particular
6414** strategy. A cost of N indicates that the cost of the strategy is similar
6415** to a linear scan of an SQLite table with N rows. A cost of log(N)
6416** indicates that the expense of the operation is similar to that of a
6417** binary search on a unique indexed field of an SQLite table with N rows.
6419** ^The estimatedRows value is an estimate of the number of rows that
6420** will be returned by the strategy.
6422** The xBestIndex method may optionally populate the idxFlags field with a
6423** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -
6424** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite
6425** assumes that the strategy may visit at most one row.
6427** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then
6428** SQLite also assumes that if a call to the xUpdate() method is made as
6429** part of the same statement to delete or update a virtual table row and the
6430** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback
6431** any database changes. In other words, if the xUpdate() returns
6432** SQLITE_CONSTRAINT, the database contents must be exactly as they were
6433** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not
6434** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by
6435** the xUpdate method are automatically rolled back by SQLite.
6437** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
6438** structure for SQLite [version 3.8.2] ([dateof:3.8.2]).
6439** If a virtual table extension is
6440** used with an SQLite version earlier than 3.8.2, the results of attempting
6441** to read or write the estimatedRows field are undefined (but are likely
6442** to included crashing the application). The estimatedRows field should
6443** therefore only be used if [sqlite3_libversion_number()] returns a
6444** value greater than or equal to 3008002. Similarly, the idxFlags field
6445** was added for [version 3.9.0] ([dateof:3.9.0]).
6446** It may therefore only be used if
6447** sqlite3_libversion_number() returns a value greater than or equal to
6448** 3009000.
6450struct sqlite3_index_info {
6451 /* Inputs */
6452 int nConstraint; /* Number of entries in aConstraint */
6453 struct sqlite3_index_constraint {
6454 int iColumn; /* Column constrained. -1 for ROWID */
6455 unsigned char op; /* Constraint operator */
6456 unsigned char usable; /* True if this constraint is usable */
6457 int iTermOffset; /* Used internally - xBestIndex should ignore */
6458 } *aConstraint; /* Table of WHERE clause constraints */
6459 int nOrderBy; /* Number of terms in the ORDER BY clause */
6460 struct sqlite3_index_orderby {
6461 int iColumn; /* Column number */
6462 unsigned char desc; /* True for DESC. False for ASC. */
6463 } *aOrderBy; /* The ORDER BY clause */
6464 /* Outputs */
6465 struct sqlite3_index_constraint_usage {
6466 int argvIndex; /* if >0, constraint is part of argv to xFilter */
6467 unsigned char omit; /* Do not code a test for this constraint */
6468 } *aConstraintUsage;
6469 int idxNum; /* Number used to identify the index */
6470 char *idxStr; /* String, possibly obtained from sqlite3_malloc */
6471 int needToFreeIdxStr; /* Free idxStr using sqlite3_free() if true */
6472 int orderByConsumed; /* True if output is already ordered */
6473 double estimatedCost; /* Estimated cost of using this index */
6474 /* Fields below are only available in SQLite 3.8.2 and later */
6475 sqlite3_int64 estimatedRows; /* Estimated number of rows returned */
6476 /* Fields below are only available in SQLite 3.9.0 and later */
6477 int idxFlags; /* Mask of SQLITE_INDEX_SCAN_* flags */
6478 /* Fields below are only available in SQLite 3.10.0 and later */
6479 sqlite3_uint64 colUsed; /* Input: Mask of columns used by statement */
6483** CAPI3REF: Virtual Table Scan Flags
6485** Virtual table implementations are allowed to set the
6486** [sqlite3_index_info].idxFlags field to some combination of
6487** these bits.
6489#define SQLITE_INDEX_SCAN_UNIQUE 1 /* Scan visits at most 1 row */
6492** CAPI3REF: Virtual Table Constraint Operator Codes
6494** These macros defined the allowed values for the
6495** [sqlite3_index_info].aConstraint[].op field. Each value represents
6496** an operator that is part of a constraint term in the wHERE clause of
6497** a query that uses a [virtual table].
6516** CAPI3REF: Register A Virtual Table Implementation
6517** METHOD: sqlite3
6519** ^These routines are used to register a new [virtual table module] name.
6520** ^Module names must be registered before
6521** creating a new [virtual table] using the module and before using a
6522** preexisting [virtual table] for the module.
6524** ^The module name is registered on the [database connection] specified
6525** by the first parameter. ^The name of the module is given by the
6526** second parameter. ^The third parameter is a pointer to
6527** the implementation of the [virtual table module]. ^The fourth
6528** parameter is an arbitrary client data pointer that is passed through
6529** into the [xCreate] and [xConnect] methods of the virtual table module
6530** when a new virtual table is be being created or reinitialized.
6532** ^The sqlite3_create_module_v2() interface has a fifth parameter which
6533** is a pointer to a destructor for the pClientData. ^SQLite will
6534** invoke the destructor function (if it is not NULL) when SQLite
6535** no longer needs the pClientData pointer. ^The destructor will also
6536** be invoked if the call to sqlite3_create_module_v2() fails.
6537** ^The sqlite3_create_module()
6538** interface is equivalent to sqlite3_create_module_v2() with a NULL
6539** destructor.
6541SQLITE_API int sqlite3_create_module(
6542 sqlite3 *db, /* SQLite connection to register module with */
6543 const char *zName, /* Name of the module */
6544 const sqlite3_module *p, /* Methods for the module */
6545 void *pClientData /* Client data for xCreate/xConnect */
6547SQLITE_API int sqlite3_create_module_v2(
6548 sqlite3 *db, /* SQLite connection to register module with */
6549 const char *zName, /* Name of the module */
6550 const sqlite3_module *p, /* Methods for the module */
6551 void *pClientData, /* Client data for xCreate/xConnect */
6552 void(*xDestroy)(void*) /* Module destructor function */
6556** CAPI3REF: Virtual Table Instance Object
6557** KEYWORDS: sqlite3_vtab
6559** Every [virtual table module] implementation uses a subclass
6560** of this object to describe a particular instance
6561** of the [virtual table]. Each subclass will
6562** be tailored to the specific needs of the module implementation.
6563** The purpose of this superclass is to define certain fields that are
6564** common to all module implementations.
6566** ^Virtual tables methods can set an error message by assigning a
6567** string obtained from [sqlite3_mprintf()] to zErrMsg. The method should
6568** take care that any prior string is freed by a call to [sqlite3_free()]
6569** prior to assigning a new string to zErrMsg. ^After the error message
6570** is delivered up to the client application, the string will be automatically
6571** freed by sqlite3_free() and the zErrMsg field will be zeroed.
6573struct sqlite3_vtab {
6574 const sqlite3_module *pModule; /* The module for this virtual table */
6575 int nRef; /* Number of open cursors */
6576 char *zErrMsg; /* Error message from sqlite3_mprintf() */
6577 /* Virtual table implementations will typically add additional fields */
6581** CAPI3REF: Virtual Table Cursor Object
6582** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
6584** Every [virtual table module] implementation uses a subclass of the
6585** following structure to describe cursors that point into the
6586** [virtual table] and are used
6587** to loop through the virtual table. Cursors are created using the
6588** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
6589** by the [sqlite3_module.xClose | xClose] method. Cursors are used
6590** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
6591** of the module. Each module implementation will define
6592** the content of a cursor structure to suit its own needs.
6594** This superclass exists in order to define fields of the cursor that
6595** are common to all implementations.
6597struct sqlite3_vtab_cursor {
6598 sqlite3_vtab *pVtab; /* Virtual table of this cursor */
6599 /* Virtual table implementations will typically add additional fields */
6603** CAPI3REF: Declare The Schema Of A Virtual Table
6605** ^The [xCreate] and [xConnect] methods of a
6606** [virtual table module] call this interface
6607** to declare the format (the names and datatypes of the columns) of
6608** the virtual tables they implement.
6610SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
6613** CAPI3REF: Overload A Function For A Virtual Table
6614** METHOD: sqlite3
6616** ^(Virtual tables can provide alternative implementations of functions
6617** using the [xFindFunction] method of the [virtual table module].
6618** But global versions of those functions
6619** must exist in order to be overloaded.)^
6621** ^(This API makes sure a global version of a function with a particular
6622** name and number of parameters exists. If no such function exists
6623** before this API is called, a new function is created.)^ ^The implementation
6624** of the new function always causes an exception to be thrown. So
6625** the new function is not good for anything by itself. Its only
6626** purpose is to be a placeholder function that can be overloaded
6627** by a [virtual table].
6629SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
6632** The interface to the virtual-table mechanism defined above (back up
6633** to a comment remarkably similar to this one) is currently considered
6634** to be experimental. The interface might change in incompatible ways.
6635** If this is a problem for you, do not use the interface at this time.
6637** When the virtual-table mechanism stabilizes, we will declare the
6638** interface fixed, support it indefinitely, and remove this comment.
6642** CAPI3REF: A Handle To An Open BLOB
6643** KEYWORDS: {BLOB handle} {BLOB handles}
6645** An instance of this object represents an open BLOB on which
6646** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
6647** ^Objects of this type are created by [sqlite3_blob_open()]
6648** and destroyed by [sqlite3_blob_close()].
6649** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
6650** can be used to read or write small subsections of the BLOB.
6651** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
6653typedef struct sqlite3_blob sqlite3_blob;
6656** CAPI3REF: Open A BLOB For Incremental I/O
6657** METHOD: sqlite3
6658** CONSTRUCTOR: sqlite3_blob
6660** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
6661** in row iRow, column zColumn, table zTable in database zDb;
6662** in other words, the same BLOB that would be selected by:
6664** <pre>
6665** SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
6666** </pre>)^
6668** ^(Parameter zDb is not the filename that contains the database, but
6669** rather the symbolic name of the database. For attached databases, this is
6670** the name that appears after the AS keyword in the [ATTACH] statement.
6671** For the main database file, the database name is "main". For TEMP
6672** tables, the database name is "temp".)^
6674** ^If the flags parameter is non-zero, then the BLOB is opened for read
6675** and write access. ^If the flags parameter is zero, the BLOB is opened for
6676** read-only access.
6678** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is stored
6679** in *ppBlob. Otherwise an [error code] is returned and, unless the error
6680** code is SQLITE_MISUSE, *ppBlob is set to NULL.)^ ^This means that, provided
6681** the API is not misused, it is always safe to call [sqlite3_blob_close()]
6682** on *ppBlob after this function it returns.
6684** This function fails with SQLITE_ERROR if any of the following are true:
6685** <ul>
6686** <li> ^(Database zDb does not exist)^,
6687** <li> ^(Table zTable does not exist within database zDb)^,
6688** <li> ^(Table zTable is a WITHOUT ROWID table)^,
6689** <li> ^(Column zColumn does not exist)^,
6690** <li> ^(Row iRow is not present in the table)^,
6691** <li> ^(The specified column of row iRow contains a value that is not
6692** a TEXT or BLOB value)^,
6693** <li> ^(Column zColumn is part of an index, PRIMARY KEY or UNIQUE
6694** constraint and the blob is being opened for read/write access)^,
6695** <li> ^([foreign key constraints | Foreign key constraints] are enabled,
6696** column zColumn is part of a [child key] definition and the blob is
6697** being opened for read/write access)^.
6698** </ul>
6700** ^Unless it returns SQLITE_MISUSE, this function sets the
6701** [database connection] error code and message accessible via
6702** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions.
6704** A BLOB referenced by sqlite3_blob_open() may be read using the
6705** [sqlite3_blob_read()] interface and modified by using
6706** [sqlite3_blob_write()]. The [BLOB handle] can be moved to a
6707** different row of the same table using the [sqlite3_blob_reopen()]
6708** interface. However, the column, table, or database of a [BLOB handle]
6709** cannot be changed after the [BLOB handle] is opened.
6711** ^(If the row that a BLOB handle points to is modified by an
6712** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
6713** then the BLOB handle is marked as "expired".
6714** This is true if any column of the row is changed, even a column
6715** other than the one the BLOB handle is open on.)^
6716** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
6717** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
6718** ^(Changes written into a BLOB prior to the BLOB expiring are not
6719** rolled back by the expiration of the BLOB. Such changes will eventually
6720** commit if the transaction continues to completion.)^
6722** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
6723** the opened blob. ^The size of a blob may not be changed by this
6724** interface. Use the [UPDATE] SQL command to change the size of a
6725** blob.
6727** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
6728** and the built-in [zeroblob] SQL function may be used to create a
6729** zero-filled blob to read or write using the incremental-blob interface.
6731** To avoid a resource leak, every open [BLOB handle] should eventually
6732** be released by a call to [sqlite3_blob_close()].
6734** See also: [sqlite3_blob_close()],
6735** [sqlite3_blob_reopen()], [sqlite3_blob_read()],
6736** [sqlite3_blob_bytes()], [sqlite3_blob_write()].
6738SQLITE_API int sqlite3_blob_open(
6739 sqlite3*,
6740 const char *zDb,
6741 const char *zTable,
6742 const char *zColumn,
6743 sqlite3_int64 iRow,
6744 int flags,
6745 sqlite3_blob **ppBlob
6749** CAPI3REF: Move a BLOB Handle to a New Row
6750** METHOD: sqlite3_blob
6752** ^This function is used to move an existing [BLOB handle] so that it points
6753** to a different row of the same database table. ^The new row is identified
6754** by the rowid value passed as the second argument. Only the row can be
6755** changed. ^The database, table and column on which the blob handle is open
6756** remain the same. Moving an existing [BLOB handle] to a new row is
6757** faster than closing the existing handle and opening a new one.
6759** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
6760** it must exist and there must be either a blob or text value stored in
6761** the nominated column.)^ ^If the new row is not present in the table, or if
6762** it does not contain a blob or text value, or if another error occurs, an
6763** SQLite error code is returned and the blob handle is considered aborted.
6764** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
6765** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
6766** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
6767** always returns zero.
6769** ^This function sets the database handle error code and message.
6771SQLITE_API int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
6774** CAPI3REF: Close A BLOB Handle
6775** DESTRUCTOR: sqlite3_blob
6777** ^This function closes an open [BLOB handle]. ^(The BLOB handle is closed
6778** unconditionally. Even if this routine returns an error code, the
6779** handle is still closed.)^
6781** ^If the blob handle being closed was opened for read-write access, and if
6782** the database is in auto-commit mode and there are no other open read-write
6783** blob handles or active write statements, the current transaction is
6784** committed. ^If an error occurs while committing the transaction, an error
6785** code is returned and the transaction rolled back.
6787** Calling this function with an argument that is not a NULL pointer or an
6788** open blob handle results in undefined behaviour. ^Calling this routine
6789** with a null pointer (such as would be returned by a failed call to
6790** [sqlite3_blob_open()]) is a harmless no-op. ^Otherwise, if this function
6791** is passed a valid open blob handle, the values returned by the
6792** sqlite3_errcode() and sqlite3_errmsg() functions are set before returning.
6794SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
6797** CAPI3REF: Return The Size Of An Open BLOB
6798** METHOD: sqlite3_blob
6800** ^Returns the size in bytes of the BLOB accessible via the
6801** successfully opened [BLOB handle] in its only argument. ^The
6802** incremental blob I/O routines can only read or overwriting existing
6803** blob content; they cannot change the size of a blob.
6805** This routine only works on a [BLOB handle] which has been created
6806** by a prior successful call to [sqlite3_blob_open()] and which has not
6807** been closed by [sqlite3_blob_close()]. Passing any other pointer in
6808** to this routine results in undefined and probably undesirable behavior.
6810SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
6813** CAPI3REF: Read Data From A BLOB Incrementally
6814** METHOD: sqlite3_blob
6816** ^(This function is used to read data from an open [BLOB handle] into a
6817** caller-supplied buffer. N bytes of data are copied into buffer Z
6818** from the open BLOB, starting at offset iOffset.)^
6820** ^If offset iOffset is less than N bytes from the end of the BLOB,
6821** [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is
6822** less than zero, [SQLITE_ERROR] is returned and no data is read.
6823** ^The size of the blob (and hence the maximum value of N+iOffset)
6824** can be determined using the [sqlite3_blob_bytes()] interface.
6826** ^An attempt to read from an expired [BLOB handle] fails with an
6827** error code of [SQLITE_ABORT].
6829** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
6830** Otherwise, an [error code] or an [extended error code] is returned.)^
6832** This routine only works on a [BLOB handle] which has been created
6833** by a prior successful call to [sqlite3_blob_open()] and which has not
6834** been closed by [sqlite3_blob_close()]. Passing any other pointer in
6835** to this routine results in undefined and probably undesirable behavior.
6837** See also: [sqlite3_blob_write()].
6839SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
6842** CAPI3REF: Write Data Into A BLOB Incrementally
6843** METHOD: sqlite3_blob
6845** ^(This function is used to write data into an open [BLOB handle] from a
6846** caller-supplied buffer. N bytes of data are copied from the buffer Z
6847** into the open BLOB, starting at offset iOffset.)^
6849** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
6850** Otherwise, an [error code] or an [extended error code] is returned.)^
6851** ^Unless SQLITE_MISUSE is returned, this function sets the
6852** [database connection] error code and message accessible via
6853** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions.
6855** ^If the [BLOB handle] passed as the first argument was not opened for
6856** writing (the flags parameter to [sqlite3_blob_open()] was zero),
6857** this function returns [SQLITE_READONLY].
6859** This function may only modify the contents of the BLOB; it is
6860** not possible to increase the size of a BLOB using this API.
6861** ^If offset iOffset is less than N bytes from the end of the BLOB,
6862** [SQLITE_ERROR] is returned and no data is written. The size of the
6863** BLOB (and hence the maximum value of N+iOffset) can be determined
6864** using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less
6865** than zero [SQLITE_ERROR] is returned and no data is written.
6867** ^An attempt to write to an expired [BLOB handle] fails with an
6868** error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred
6869** before the [BLOB handle] expired are not rolled back by the
6870** expiration of the handle, though of course those changes might
6871** have been overwritten by the statement that expired the BLOB handle
6872** or by other independent statements.
6874** This routine only works on a [BLOB handle] which has been created
6875** by a prior successful call to [sqlite3_blob_open()] and which has not
6876** been closed by [sqlite3_blob_close()]. Passing any other pointer in
6877** to this routine results in undefined and probably undesirable behavior.
6879** See also: [sqlite3_blob_read()].
6881SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
6884** CAPI3REF: Virtual File System Objects
6886** A virtual filesystem (VFS) is an [sqlite3_vfs] object
6887** that SQLite uses to interact
6888** with the underlying operating system. Most SQLite builds come with a
6889** single default VFS that is appropriate for the host computer.
6890** New VFSes can be registered and existing VFSes can be unregistered.
6891** The following interfaces are provided.
6893** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
6894** ^Names are case sensitive.
6895** ^Names are zero-terminated UTF-8 strings.
6896** ^If there is no match, a NULL pointer is returned.
6897** ^If zVfsName is NULL then the default VFS is returned.
6899** ^New VFSes are registered with sqlite3_vfs_register().
6900** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
6901** ^The same VFS can be registered multiple times without injury.
6902** ^To make an existing VFS into the default VFS, register it again
6903** with the makeDflt flag set. If two different VFSes with the
6904** same name are registered, the behavior is undefined. If a
6905** VFS is registered with a name that is NULL or an empty string,
6906** then the behavior is undefined.
6908** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
6909** ^(If the default VFS is unregistered, another VFS is chosen as
6910** the default. The choice for the new VFS is arbitrary.)^
6912SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
6913SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
6914SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
6917** CAPI3REF: Mutexes
6919** The SQLite core uses these routines for thread
6920** synchronization. Though they are intended for internal
6921** use by SQLite, code that links against SQLite is
6922** permitted to use any of these routines.
6924** The SQLite source code contains multiple implementations
6925** of these mutex routines. An appropriate implementation
6926** is selected automatically at compile-time. The following
6927** implementations are available in the SQLite core:
6929** <ul>
6931** <li> SQLITE_MUTEX_W32
6933** </ul>
6935** The SQLITE_MUTEX_NOOP implementation is a set of routines
6936** that does no real locking and is appropriate for use in
6937** a single-threaded application. The SQLITE_MUTEX_PTHREADS and
6938** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
6939** and Windows.
6941** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
6942** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
6943** implementation is included with the library. In this case the
6944** application must supply a custom mutex implementation using the
6945** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
6946** before calling sqlite3_initialize() or any other public sqlite3_
6947** function that calls sqlite3_initialize().
6949** ^The sqlite3_mutex_alloc() routine allocates a new
6950** mutex and returns a pointer to it. ^The sqlite3_mutex_alloc()
6951** routine returns NULL if it is unable to allocate the requested
6952** mutex. The argument to sqlite3_mutex_alloc() must one of these
6953** integer constants:
6955** <ul>
6970** </ul>
6972** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
6973** cause sqlite3_mutex_alloc() to create
6974** a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
6975** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
6976** The mutex implementation does not need to make a distinction
6977** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
6978** not want to. SQLite will only request a recursive mutex in
6979** cases where it really needs one. If a faster non-recursive mutex
6980** implementation is available on the host platform, the mutex subsystem
6981** might return such a mutex in response to SQLITE_MUTEX_FAST.
6983** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
6985** a pointer to a static preexisting mutex. ^Nine static mutexes are
6986** used by the current version of SQLite. Future versions of SQLite
6987** may add additional static mutexes. Static mutexes are for internal
6988** use by SQLite only. Applications that use SQLite mutexes should
6989** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
6992** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
6993** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
6994** returns a different mutex on every call. ^For the static
6995** mutex types, the same mutex is returned on every call that has
6996** the same type number.
6998** ^The sqlite3_mutex_free() routine deallocates a previously
6999** allocated dynamic mutex. Attempting to deallocate a static
7000** mutex results in undefined behavior.
7002** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
7003** to enter a mutex. ^If another thread is already within the mutex,
7004** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
7005** SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
7006** upon successful entry. ^(Mutexes created using
7007** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
7008** In such cases, the
7009** mutex must be exited an equal number of times before another thread
7010** can enter.)^ If the same thread tries to enter any mutex other
7011** than an SQLITE_MUTEX_RECURSIVE more than once, the behavior is undefined.
7013** ^(Some systems (for example, Windows 95) do not support the operation
7014** implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try()
7015** will always return SQLITE_BUSY. The SQLite core only ever uses
7016** sqlite3_mutex_try() as an optimization so this is acceptable
7017** behavior.)^
7019** ^The sqlite3_mutex_leave() routine exits a mutex that was
7020** previously entered by the same thread. The behavior
7021** is undefined if the mutex is not currently entered by the
7022** calling thread or is not currently allocated.
7024** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
7025** sqlite3_mutex_leave() is a NULL pointer, then all three routines
7026** behave as no-ops.
7028** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
7030SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
7031SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
7032SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
7033SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
7034SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
7037** CAPI3REF: Mutex Methods Object
7039** An instance of this structure defines the low-level routines
7040** used to allocate and use mutexes.
7042** Usually, the default mutex implementations provided by SQLite are
7043** sufficient, however the application has the option of substituting a custom
7044** implementation for specialized deployments or systems for which SQLite
7045** does not provide a suitable implementation. In this case, the application
7046** creates and populates an instance of this structure to pass
7047** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
7048** Additionally, an instance of this structure can be used as an
7049** output variable when querying the system for the current mutex
7050** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
7052** ^The xMutexInit method defined by this structure is invoked as
7053** part of system initialization by the sqlite3_initialize() function.
7054** ^The xMutexInit routine is called by SQLite exactly once for each
7055** effective call to [sqlite3_initialize()].
7057** ^The xMutexEnd method defined by this structure is invoked as
7058** part of system shutdown by the sqlite3_shutdown() function. The
7059** implementation of this method is expected to release all outstanding
7060** resources obtained by the mutex methods implementation, especially
7061** those obtained by the xMutexInit method. ^The xMutexEnd()
7062** interface is invoked exactly once for each call to [sqlite3_shutdown()].
7064** ^(The remaining seven methods defined by this structure (xMutexAlloc,
7065** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
7066** xMutexNotheld) implement the following interfaces (respectively):
7068** <ul>
7069** <li> [sqlite3_mutex_alloc()] </li>
7070** <li> [sqlite3_mutex_free()] </li>
7071** <li> [sqlite3_mutex_enter()] </li>
7072** <li> [sqlite3_mutex_try()] </li>
7073** <li> [sqlite3_mutex_leave()] </li>
7074** <li> [sqlite3_mutex_held()] </li>
7075** <li> [sqlite3_mutex_notheld()] </li>
7076** </ul>)^
7078** The only difference is that the public sqlite3_XXX functions enumerated
7079** above silently ignore any invocations that pass a NULL pointer instead
7080** of a valid mutex handle. The implementations of the methods defined
7081** by this structure are not required to handle this case, the results
7082** of passing a NULL pointer instead of a valid mutex handle are undefined
7083** (i.e. it is acceptable to provide an implementation that segfaults if
7084** it is passed a NULL pointer).
7086** The xMutexInit() method must be threadsafe. It must be harmless to
7087** invoke xMutexInit() multiple times within the same process and without
7088** intervening calls to xMutexEnd(). Second and subsequent calls to
7089** xMutexInit() must be no-ops.
7091** xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
7092** and its associates). Similarly, xMutexAlloc() must not use SQLite memory
7093** allocation for a static mutex. ^However xMutexAlloc() may use SQLite
7094** memory allocation for a fast or recursive mutex.
7096** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
7097** called, but only if the prior call to xMutexInit returned SQLITE_OK.
7098** If xMutexInit fails in any way, it is expected to clean up after itself
7099** prior to returning.
7101typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
7102struct sqlite3_mutex_methods {
7103 int (*xMutexInit)(void);
7104 int (*xMutexEnd)(void);
7105 sqlite3_mutex *(*xMutexAlloc)(int);
7106 void (*xMutexFree)(sqlite3_mutex *);
7107 void (*xMutexEnter)(sqlite3_mutex *);
7108 int (*xMutexTry)(sqlite3_mutex *);
7109 void (*xMutexLeave)(sqlite3_mutex *);
7110 int (*xMutexHeld)(sqlite3_mutex *);
7111 int (*xMutexNotheld)(sqlite3_mutex *);
7115** CAPI3REF: Mutex Verification Routines
7117** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
7118** are intended for use inside assert() statements. The SQLite core
7119** never uses these routines except inside an assert() and applications
7120** are advised to follow the lead of the core. The SQLite core only
7121** provides implementations for these routines when it is compiled
7122** with the SQLITE_DEBUG flag. External mutex implementations
7123** are only required to provide these routines if SQLITE_DEBUG is
7124** defined and if NDEBUG is not defined.
7126** These routines should return true if the mutex in their argument
7127** is held or not held, respectively, by the calling thread.
7129** The implementation is not required to provide versions of these
7130** routines that actually work. If the implementation does not provide working
7131** versions of these routines, it should at least provide stubs that always
7132** return true so that one does not get spurious assertion failures.
7134** If the argument to sqlite3_mutex_held() is a NULL pointer then
7135** the routine should return 1. This seems counter-intuitive since
7136** clearly the mutex cannot be held if it does not exist. But
7137** the reason the mutex does not exist is because the build is not
7138** using mutexes. And we do not want the assert() containing the
7139** call to sqlite3_mutex_held() to fail, so a non-zero return is
7140** the appropriate thing to do. The sqlite3_mutex_notheld()
7141** interface should also return 1 when given a NULL pointer.
7143#ifndef NDEBUG
7144SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
7145SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
7149** CAPI3REF: Mutex Types
7151** The [sqlite3_mutex_alloc()] interface takes a single argument
7152** which is one of these integer constants.
7154** The set of static mutexes may change from one SQLite release to the
7155** next. Applications that override the built-in mutex logic must be
7156** prepared to accommodate additional static mutexes.
7158#define SQLITE_MUTEX_FAST 0
7161#define SQLITE_MUTEX_STATIC_MEM 3 /* sqlite3_malloc() */
7163#define SQLITE_MUTEX_STATIC_OPEN 4 /* sqlite3BtreeOpen() */
7164#define SQLITE_MUTEX_STATIC_PRNG 5 /* sqlite3_randomness() */
7165#define SQLITE_MUTEX_STATIC_LRU 6 /* lru page list */
7167#define SQLITE_MUTEX_STATIC_PMEM 7 /* sqlite3PageMalloc() */
7168#define SQLITE_MUTEX_STATIC_APP1 8 /* For use by application */
7169#define SQLITE_MUTEX_STATIC_APP2 9 /* For use by application */
7170#define SQLITE_MUTEX_STATIC_APP3 10 /* For use by application */
7171#define SQLITE_MUTEX_STATIC_VFS1 11 /* For use by built-in VFS */
7172#define SQLITE_MUTEX_STATIC_VFS2 12 /* For use by extension VFS */
7173#define SQLITE_MUTEX_STATIC_VFS3 13 /* For use by application VFS */
7176** CAPI3REF: Retrieve the mutex for a database connection
7177** METHOD: sqlite3
7179** ^This interface returns a pointer the [sqlite3_mutex] object that
7180** serializes access to the [database connection] given in the argument
7181** when the [threading mode] is Serialized.
7182** ^If the [threading mode] is Single-thread or Multi-thread then this
7183** routine returns a NULL pointer.
7185SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
7188** CAPI3REF: Low-Level Control Of Database Files
7189** METHOD: sqlite3
7190** KEYWORDS: {file control}
7192** ^The [sqlite3_file_control()] interface makes a direct call to the
7193** xFileControl method for the [sqlite3_io_methods] object associated
7194** with a particular database identified by the second argument. ^The
7195** name of the database is "main" for the main database or "temp" for the
7196** TEMP database, or the name that appears after the AS keyword for
7197** databases that are added using the [ATTACH] SQL command.
7198** ^A NULL pointer can be used in place of "main" to refer to the
7199** main database file.
7200** ^The third and fourth parameters to this routine
7201** are passed directly through to the second and third parameters of
7202** the xFileControl method. ^The return value of the xFileControl
7203** method becomes the return value of this routine.
7205** A few opcodes for [sqlite3_file_control()] are handled directly
7206** by the SQLite core and never invoke the
7207** sqlite3_io_methods.xFileControl method.
7208** ^The [SQLITE_FCNTL_FILE_POINTER] value for the op parameter causes
7209** a pointer to the underlying [sqlite3_file] object to be written into
7210** the space pointed to by the 4th parameter. The
7211** [SQLITE_FCNTL_JOURNAL_POINTER] works similarly except that it returns
7212** the [sqlite3_file] object associated with the journal file instead of
7213** the main database. The [SQLITE_FCNTL_VFS_POINTER] opcode returns
7214** a pointer to the underlying [sqlite3_vfs] object for the file.
7215** The [SQLITE_FCNTL_DATA_VERSION] returns the data version counter
7216** from the pager.
7218** ^If the second parameter (zDbName) does not match the name of any
7219** open database file, then SQLITE_ERROR is returned. ^This error
7220** code is not remembered and will not be recalled by [sqlite3_errcode()]
7221** or [sqlite3_errmsg()]. The underlying xFileControl method might
7222** also return SQLITE_ERROR. There is no way to distinguish between
7223** an incorrect zDbName and an SQLITE_ERROR return from the underlying
7224** xFileControl method.
7226** See also: [file control opcodes]
7228SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
7231** CAPI3REF: Testing Interface
7233** ^The sqlite3_test_control() interface is used to read out internal
7234** state of SQLite and to inject faults into SQLite for testing
7235** purposes. ^The first parameter is an operation code that determines
7236** the number, meaning, and operation of all subsequent parameters.
7238** This interface is not for use by applications. It exists solely
7239** for verifying the correct operation of the SQLite library. Depending
7240** on how the SQLite library is compiled, this interface might not exist.
7242** The details of the operation codes, their meanings, the parameters
7243** they take, and what they do are all subject to change without notice.
7244** Unlike most of the SQLite API, this function is not guaranteed to
7245** operate consistently from one release to the next.
7247SQLITE_API int sqlite3_test_control(int op, ...);
7250** CAPI3REF: Testing Interface Operation Codes
7252** These constants are the valid operation code parameters used
7253** as the first argument to [sqlite3_test_control()].
7255** These parameters and their meanings are subject to change
7256** without notice. These values are for testing purposes only.
7257** Applications should not use any of these parameters or the
7258** [sqlite3_test_control()] interface.
7285#define SQLITE_TESTCTRL_LAST 26 /* Largest TESTCTRL */
7288** CAPI3REF: SQL Keyword Checking
7290** These routines provide access to the set of SQL language keywords
7291** recognized by SQLite. Applications can uses these routines to determine
7292** whether or not a specific identifier needs to be escaped (for example,
7293** by enclosing in double-quotes) so as not to confuse the parser.
7295** The sqlite3_keyword_count() interface returns the number of distinct
7296** keywords understood by SQLite.
7298** The sqlite3_keyword_name(N,Z,L) interface finds the N-th keyword and
7299** makes *Z point to that keyword expressed as UTF8 and writes the number
7300** of bytes in the keyword into *L. The string that *Z points to is not
7301** zero-terminated. The sqlite3_keyword_name(N,Z,L) routine returns
7302** SQLITE_OK if N is within bounds and SQLITE_ERROR if not. If either Z
7303** or L are NULL or invalid pointers then calls to
7304** sqlite3_keyword_name(N,Z,L) result in undefined behavior.
7306** The sqlite3_keyword_check(Z,L) interface checks to see whether or not
7307** the L-byte UTF8 identifier that Z points to is a keyword, returning non-zero
7308** if it is and zero if not.
7310** The parser used by SQLite is forgiving. It is often possible to use
7311** a keyword as an identifier as long as such use does not result in a
7312** parsing ambiguity. For example, the statement
7313** "CREATE TABLE BEGIN(REPLACE,PRAGMA,END);" is accepted by SQLite, and
7314** creates a new table named "BEGIN" with three columns named
7315** "REPLACE", "PRAGMA", and "END". Nevertheless, best practice is to avoid
7316** using keywords as identifiers. Common techniques used to avoid keyword
7317** name collisions include:
7318** <ul>
7319** <li> Put all identifier names inside double-quotes. This is the official
7320** SQL way to escape identifier names.
7321** <li> Put identifier names inside &#91;...&#93;. This is not standard SQL,
7322** but it is what SQL Server does and so lots of programmers use this
7323** technique.
7324** <li> Begin every identifier with the letter "Z" as no SQL keywords start
7325** with "Z".
7326** <li> Include a digit somewhere in every identifier name.
7327** </ul>
7329** Note that the number of keywords understood by SQLite can depend on
7330** compile-time options. For example, "VACUUM" is not a keyword if
7331** SQLite is compiled with the [-DSQLITE_OMIT_VACUUM] option. Also,
7332** new keywords may be added to future releases of SQLite.
7334SQLITE_API int sqlite3_keyword_count(void);
7335SQLITE_API int sqlite3_keyword_name(int,const char**,int*);
7336SQLITE_API int sqlite3_keyword_check(const char*,int);
7339** CAPI3REF: Dynamic String Object
7340** KEYWORDS: {dynamic string}
7342** An instance of the sqlite3_str object contains a dynamically-sized
7343** string under construction.
7345** The lifecycle of an sqlite3_str object is as follows:
7346** <ol>
7347** <li> ^The sqlite3_str object is created using [sqlite3_str_new()].
7348** <li> ^Text is appended to the sqlite3_str object using various
7349** methods, such as [sqlite3_str_appendf()].
7350** <li> ^The sqlite3_str object is destroyed and the string it created
7351** is returned using the [sqlite3_str_finish()] interface.
7352** </ol>
7354typedef struct sqlite3_str sqlite3_str;
7357** CAPI3REF: Create A New Dynamic String Object
7358** CONSTRUCTOR: sqlite3_str
7360** ^The [sqlite3_str_new(D)] interface allocates and initializes
7361** a new [sqlite3_str] object. To avoid memory leaks, the object returned by
7362** [sqlite3_str_new()] must be freed by a subsequent call to
7363** [sqlite3_str_finish(X)].
7365** ^The [sqlite3_str_new(D)] interface always returns a pointer to a
7366** valid [sqlite3_str] object, though in the event of an out-of-memory
7367** error the returned object might be a special singleton that will
7368** silently reject new text, always return SQLITE_NOMEM from
7369** [sqlite3_str_errcode()], always return 0 for
7370** [sqlite3_str_length()], and always return NULL from
7371** [sqlite3_str_finish(X)]. It is always safe to use the value
7372** returned by [sqlite3_str_new(D)] as the sqlite3_str parameter
7373** to any of the other [sqlite3_str] methods.
7375** The D parameter to [sqlite3_str_new(D)] may be NULL. If the
7376** D parameter in [sqlite3_str_new(D)] is not NULL, then the maximum
7377** length of the string contained in the [sqlite3_str] object will be
7378** the value set for [sqlite3_limit](D,[SQLITE_LIMIT_LENGTH]) instead
7379** of [SQLITE_MAX_LENGTH].
7381SQLITE_API sqlite3_str *sqlite3_str_new(sqlite3*);
7384** CAPI3REF: Finalize A Dynamic String
7385** DESTRUCTOR: sqlite3_str
7387** ^The [sqlite3_str_finish(X)] interface destroys the sqlite3_str object X
7388** and returns a pointer to a memory buffer obtained from [sqlite3_malloc64()]
7389** that contains the constructed string. The calling application should
7390** pass the returned value to [sqlite3_free()] to avoid a memory leak.
7391** ^The [sqlite3_str_finish(X)] interface may return a NULL pointer if any
7392** errors were encountered during construction of the string. ^The
7393** [sqlite3_str_finish(X)] interface will also return a NULL pointer if the
7394** string in [sqlite3_str] object X is zero bytes long.
7396SQLITE_API char *sqlite3_str_finish(sqlite3_str*);
7399** CAPI3REF: Add Content To A Dynamic String
7400** METHOD: sqlite3_str
7402** These interfaces add content to an sqlite3_str object previously obtained
7403** from [sqlite3_str_new()].
7405** ^The [sqlite3_str_appendf(X,F,...)] and
7406** [sqlite3_str_vappendf(X,F,V)] interfaces uses the [built-in printf]
7407** functionality of SQLite to append formatted text onto the end of
7408** [sqlite3_str] object X.
7410** ^The [sqlite3_str_append(X,S,N)] method appends exactly N bytes from string S
7411** onto the end of the [sqlite3_str] object X. N must be non-negative.
7412** S must contain at least N non-zero bytes of content. To append a
7413** zero-terminated string in its entirety, use the [sqlite3_str_appendall()]
7414** method instead.
7416** ^The [sqlite3_str_appendall(X,S)] method appends the complete content of
7417** zero-terminated string S onto the end of [sqlite3_str] object X.
7419** ^The [sqlite3_str_appendchar(X,N,C)] method appends N copies of the
7420** single-byte character C onto the end of [sqlite3_str] object X.
7421** ^This method can be used, for example, to add whitespace indentation.
7423** ^The [sqlite3_str_reset(X)] method resets the string under construction
7424** inside [sqlite3_str] object X back to zero bytes in length.
7426** These methods do not return a result code. ^If an error occurs, that fact
7427** is recorded in the [sqlite3_str] object and can be recovered by a
7428** subsequent call to [sqlite3_str_errcode(X)].
7430SQLITE_API void sqlite3_str_appendf(sqlite3_str*, const char *zFormat, ...);
7431SQLITE_API void sqlite3_str_vappendf(sqlite3_str*, const char *zFormat, va_list);
7432SQLITE_API void sqlite3_str_append(sqlite3_str*, const char *zIn, int N);
7433SQLITE_API void sqlite3_str_appendall(sqlite3_str*, const char *zIn);
7434SQLITE_API void sqlite3_str_appendchar(sqlite3_str*, int N, char C);
7435SQLITE_API void sqlite3_str_reset(sqlite3_str*);
7438** CAPI3REF: Status Of A Dynamic String
7439** METHOD: sqlite3_str
7441** These interfaces return the current status of an [sqlite3_str] object.
7443** ^If any prior errors have occurred while constructing the dynamic string
7444** in sqlite3_str X, then the [sqlite3_str_errcode(X)] method will return
7445** an appropriate error code. ^The [sqlite3_str_errcode(X)] method returns
7446** [SQLITE_NOMEM] following any out-of-memory error, or
7447** [SQLITE_TOOBIG] if the size of the dynamic string exceeds
7448** [SQLITE_MAX_LENGTH], or [SQLITE_OK] if there have been no errors.
7450** ^The [sqlite3_str_length(X)] method returns the current length, in bytes,
7451** of the dynamic string under construction in [sqlite3_str] object X.
7452** ^The length returned by [sqlite3_str_length(X)] does not include the
7453** zero-termination byte.
7455** ^The [sqlite3_str_value(X)] method returns a pointer to the current
7456** content of the dynamic string under construction in X. The value
7457** returned by [sqlite3_str_value(X)] is managed by the sqlite3_str object X
7458** and might be freed or altered by any subsequent method on the same
7459** [sqlite3_str] object. Applications must not used the pointer returned
7460** [sqlite3_str_value(X)] after any subsequent method call on the same
7461** object. ^Applications may change the content of the string returned
7462** by [sqlite3_str_value(X)] as long as they do not write into any bytes
7463** outside the range of 0 to [sqlite3_str_length(X)] and do not read or
7464** write any byte after any subsequent sqlite3_str method call.
7466SQLITE_API int sqlite3_str_errcode(sqlite3_str*);
7467SQLITE_API int sqlite3_str_length(sqlite3_str*);
7468SQLITE_API char *sqlite3_str_value(sqlite3_str*);
7471** CAPI3REF: SQLite Runtime Status
7473** ^These interfaces are used to retrieve runtime status information
7474** about the performance of SQLite, and optionally to reset various
7475** highwater marks. ^The first argument is an integer code for
7476** the specific parameter to measure. ^(Recognized integer codes
7477** are of the form [status parameters | SQLITE_STATUS_...].)^
7478** ^The current value of the parameter is returned into *pCurrent.
7479** ^The highest recorded value is returned in *pHighwater. ^If the
7480** resetFlag is true, then the highest record value is reset after
7481** *pHighwater is written. ^(Some parameters do not record the highest
7482** value. For those parameters
7483** nothing is written into *pHighwater and the resetFlag is ignored.)^
7484** ^(Other parameters record only the highwater mark and not the current
7485** value. For these latter parameters nothing is written into *pCurrent.)^
7487** ^The sqlite3_status() and sqlite3_status64() routines return
7488** SQLITE_OK on success and a non-zero [error code] on failure.
7490** If either the current value or the highwater mark is too large to
7491** be represented by a 32-bit integer, then the values returned by
7492** sqlite3_status() are undefined.
7494** See also: [sqlite3_db_status()]
7496SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
7497SQLITE_API int sqlite3_status64(
7498 int op,
7499 sqlite3_int64 *pCurrent,
7500 sqlite3_int64 *pHighwater,
7501 int resetFlag
7506** CAPI3REF: Status Parameters
7507** KEYWORDS: {status parameters}
7509** These integer constants designate various run-time status parameters
7510** that can be returned by [sqlite3_status()].
7512** <dl>
7514** <dd>This parameter is the current amount of memory checked out
7515** using [sqlite3_malloc()], either directly or indirectly. The
7516** figure includes calls made to [sqlite3_malloc()] by the application
7517** and internal memory usage by the SQLite library. Auxiliary page-cache
7518** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
7519** this parameter. The amount returned is the sum of the allocation
7520** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
7523** <dd>This parameter records the largest memory allocation request
7524** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
7525** internal equivalents). Only the value returned in the
7526** *pHighwater parameter to [sqlite3_status()] is of interest.
7527** The value written into the *pCurrent parameter is undefined.</dd>)^
7530** <dd>This parameter records the number of separate memory allocations
7531** currently checked out.</dd>)^
7534** <dd>This parameter returns the number of pages used out of the
7535** [pagecache memory allocator] that was configured using
7537** value returned is in pages, not in bytes.</dd>)^
7541** <dd>This parameter returns the number of bytes of page cache
7542** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
7543** buffer and where forced to overflow to [sqlite3_malloc()]. The
7544** returned value includes allocations that overflowed because they
7545** where too large (they were larger than the "sz" parameter to
7546** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
7547** no space was left in the page cache.</dd>)^
7550** <dd>This parameter records the largest memory allocation request
7551** handed to [pagecache memory allocator]. Only the value returned in the
7552** *pHighwater parameter to [sqlite3_status()] is of interest.
7553** The value written into the *pCurrent parameter is undefined.</dd>)^
7556** <dd>No longer used.</dd>
7559** <dd>No longer used.</dd>
7562** <dd>No longer used.</dd>
7565** <dd>The *pHighwater parameter records the deepest parser stack.
7566** The *pCurrent value is undefined. The *pHighwater value is only
7567** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
7568** </dl>
7570** New status parameters may be added from time to time.
7584** CAPI3REF: Database Connection Status
7585** METHOD: sqlite3
7587** ^This interface is used to retrieve runtime status information
7588** about a single [database connection]. ^The first argument is the
7589** database connection object to be interrogated. ^The second argument
7590** is an integer constant, taken from the set of
7591** [SQLITE_DBSTATUS options], that
7592** determines the parameter to interrogate. The set of
7593** [SQLITE_DBSTATUS options] is likely
7594** to grow in future releases of SQLite.
7596** ^The current value of the requested parameter is written into *pCur
7597** and the highest instantaneous value is written into *pHiwtr. ^If
7598** the resetFlg is true, then the highest instantaneous value is
7599** reset back down to the current value.
7601** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
7602** non-zero [error code] on failure.
7604** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
7606SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
7609** CAPI3REF: Status Parameters for database connections
7612** These constants are the available integer "verbs" that can be passed as
7613** the second argument to the [sqlite3_db_status()] interface.
7615** New verbs may be added in future releases of SQLite. Existing verbs
7616** might be discontinued. Applications should check the return code from
7617** [sqlite3_db_status()] to make sure that the call worked.
7618** The [sqlite3_db_status()] interface will return a non-zero error code
7619** if a discontinued or unsupported verb is invoked.
7621** <dl>
7623** <dd>This parameter returns the number of lookaside memory slots currently
7624** checked out.</dd>)^
7627** <dd>This parameter returns the number malloc attempts that were
7628** satisfied using lookaside memory. Only the high-water value is meaningful;
7629** the current value is always zero.)^
7633** <dd>This parameter returns the number malloc attempts that might have
7634** been satisfied using lookaside memory but failed due to the amount of
7635** memory requested being larger than the lookaside slot size.
7636** Only the high-water value is meaningful;
7637** the current value is always zero.)^
7641** <dd>This parameter returns the number malloc attempts that might have
7642** been satisfied using lookaside memory but failed due to all lookaside
7643** memory already being in use.
7644** Only the high-water value is meaningful;
7645** the current value is always zero.)^
7648** <dd>This parameter returns the approximate number of bytes of heap
7649** memory used by all pager caches associated with the database connection.)^
7650** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
7654** <dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
7655** pager cache is shared between two or more connections the bytes of heap
7656** memory used by that pager cache is divided evenly between the attached
7657** connections.)^ In other words, if none of the pager caches associated
7658** with the database connection are shared, this request returns the same
7659** value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
7660** shared, the value returned by this call will be smaller than that returned
7661** by DBSTATUS_CACHE_USED. ^The highwater mark associated with
7665** <dd>This parameter returns the approximate number of bytes of heap
7666** memory used to store the schema for all databases associated
7667** with the connection - main, temp, and any [ATTACH]-ed databases.)^
7668** ^The full amount of memory used by the schemas is reported, even if the
7669** schema memory is shared with other database connections due to
7670** [shared cache mode] being enabled.
7671** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
7674** <dd>This parameter returns the approximate number of bytes of heap
7675** and lookaside memory used by all prepared statements associated with
7676** the database connection.)^
7677** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
7678** </dd>
7681** <dd>This parameter returns the number of pager cache hits that have
7682** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT
7683** is always 0.
7684** </dd>
7687** <dd>This parameter returns the number of pager cache misses that have
7688** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS
7689** is always 0.
7690** </dd>
7693** <dd>This parameter returns the number of dirty cache entries that have
7694** been written to disk. Specifically, the number of pages written to the
7695** wal file in wal mode databases, or the number of pages written to the
7696** database file in rollback mode databases. Any pages written as part of
7697** transaction rollback or database recovery operations are not included.
7698** If an IO or other error occurs while writing a page to disk, the effect
7699** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The
7700** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
7701** </dd>
7704** <dd>This parameter returns the number of dirty cache entries that have
7705** been written to disk in the middle of a transaction due to the page
7706** cache overflowing. Transactions are more efficient if they are written
7707** to disk all at once. When pages spill mid-transaction, that introduces
7708** additional overhead. This parameter can be used help identify
7709** inefficiencies that can be resolve by increasing the cache size.
7710** </dd>
7713** <dd>This parameter returns zero for the current value if and only if
7714** all foreign key constraints (deferred or immediate) have been
7715** resolved.)^ ^The highwater mark is always 0.
7716** </dd>
7717** </dl>
7732#define SQLITE_DBSTATUS_MAX 12 /* Largest defined DBSTATUS */
7736** CAPI3REF: Prepared Statement Status
7737** METHOD: sqlite3_stmt
7739** ^(Each prepared statement maintains various
7740** [SQLITE_STMTSTATUS counters] that measure the number
7741** of times it has performed specific operations.)^ These counters can
7742** be used to monitor the performance characteristics of the prepared
7743** statements. For example, if the number of table steps greatly exceeds
7744** the number of table searches or result rows, that would tend to indicate
7745** that the prepared statement is using a full table scan rather than
7746** an index.
7748** ^(This interface is used to retrieve and reset counter values from
7749** a [prepared statement]. The first argument is the prepared statement
7750** object to be interrogated. The second argument
7751** is an integer code for a specific [SQLITE_STMTSTATUS counter]
7752** to be interrogated.)^
7753** ^The current value of the requested counter is returned.
7754** ^If the resetFlg is true, then the counter is reset to zero after this
7755** interface call returns.
7757** See also: [sqlite3_status()] and [sqlite3_db_status()].
7759SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
7762** CAPI3REF: Status Parameters for prepared statements
7765** These preprocessor macros define integer codes that name counter
7766** values associated with the [sqlite3_stmt_status()] interface.
7767** The meanings of the various counters are as follows:
7769** <dl>
7771** <dd>^This is the number of times that SQLite has stepped forward in
7772** a table as part of a full table scan. Large numbers for this counter
7773** may indicate opportunities for performance improvement through
7774** careful use of indices.</dd>
7777** <dd>^This is the number of sort operations that have occurred.
7778** A non-zero value in this counter may indicate an opportunity to
7779** improvement performance through careful use of indices.</dd>
7782** <dd>^This is the number of rows inserted into transient indices that
7783** were created automatically in order to help joins run faster.
7784** A non-zero value in this counter may indicate an opportunity to
7785** improvement performance by adding permanent indices that do not
7786** need to be reinitialized each time the statement is run.</dd>
7789** <dd>^This is the number of virtual machine operations executed
7790** by the prepared statement if that number is less than or equal
7791** to 2147483647. The number of virtual machine operations can be
7792** used as a proxy for the total work done by the prepared statement.
7793** If the number of virtual machine operations exceeds 2147483647
7794** then the value returned by this statement status code is undefined.
7797** <dd>^This is the number of times that the prepare statement has been
7798** automatically regenerated due to schema changes or change to
7799** [bound parameters] that might affect the query plan.
7802** <dd>^This is the number of times that the prepared statement has
7803** been run. A single "run" for the purposes of this counter is one
7804** or more calls to [sqlite3_step()] followed by a call to [sqlite3_reset()].
7805** The counter is incremented on the first [sqlite3_step()] call of each
7806** cycle.
7809** <dd>^This is the approximate number of bytes of heap memory
7810** used to store the prepared statement. ^This value is not actually
7811** a counter, and so the resetFlg parameter to sqlite3_stmt_status()
7812** is ignored when the opcode is SQLITE_STMTSTATUS_MEMUSED.
7813** </dd>
7814** </dl>
7825** CAPI3REF: Custom Page Cache Object
7827** The sqlite3_pcache type is opaque. It is implemented by
7828** the pluggable module. The SQLite core has no knowledge of
7829** its size or internal structure and never deals with the
7830** sqlite3_pcache object except by holding and passing pointers
7831** to the object.
7833** See [sqlite3_pcache_methods2] for additional information.
7835typedef struct sqlite3_pcache sqlite3_pcache;
7838** CAPI3REF: Custom Page Cache Object
7840** The sqlite3_pcache_page object represents a single page in the
7841** page cache. The page cache will allocate instances of this
7842** object. Various methods of the page cache use pointers to instances
7843** of this object as parameters or as their return value.
7845** See [sqlite3_pcache_methods2] for additional information.
7847typedef struct sqlite3_pcache_page sqlite3_pcache_page;
7848struct sqlite3_pcache_page {
7849 void *pBuf; /* The content of the page */
7850 void *pExtra; /* Extra information associated with the page */
7854** CAPI3REF: Application Defined Page Cache.
7855** KEYWORDS: {page cache}
7857** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can
7858** register an alternative page cache implementation by passing in an
7859** instance of the sqlite3_pcache_methods2 structure.)^
7860** In many applications, most of the heap memory allocated by
7861** SQLite is used for the page cache.
7862** By implementing a
7863** custom page cache using this API, an application can better control
7864** the amount of memory consumed by SQLite, the way in which
7865** that memory is allocated and released, and the policies used to
7866** determine exactly which parts of a database file are cached and for
7867** how long.
7869** The alternative page cache mechanism is an
7870** extreme measure that is only needed by the most demanding applications.
7871** The built-in page cache is recommended for most uses.
7873** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an
7874** internal buffer by SQLite within the call to [sqlite3_config]. Hence
7875** the application may discard the parameter after the call to
7876** [sqlite3_config()] returns.)^
7878** [[the xInit() page cache method]]
7879** ^(The xInit() method is called once for each effective
7880** call to [sqlite3_initialize()])^
7881** (usually only once during the lifetime of the process). ^(The xInit()
7882** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^
7883** The intent of the xInit() method is to set up global data structures
7884** required by the custom page cache implementation.
7885** ^(If the xInit() method is NULL, then the
7886** built-in default page cache is used instead of the application defined
7887** page cache.)^
7889** [[the xShutdown() page cache method]]
7890** ^The xShutdown() method is called by [sqlite3_shutdown()].
7891** It can be used to clean up
7892** any outstanding resources before process shutdown, if required.
7893** ^The xShutdown() method may be NULL.
7895** ^SQLite automatically serializes calls to the xInit method,
7896** so the xInit method need not be threadsafe. ^The
7897** xShutdown method is only called from [sqlite3_shutdown()] so it does
7898** not need to be threadsafe either. All other methods must be threadsafe
7899** in multithreaded applications.
7901** ^SQLite will never invoke xInit() more than once without an intervening
7902** call to xShutdown().
7904** [[the xCreate() page cache methods]]
7905** ^SQLite invokes the xCreate() method to construct a new cache instance.
7906** SQLite will typically create one cache instance for each open database file,
7907** though this is not guaranteed. ^The
7908** first parameter, szPage, is the size in bytes of the pages that must
7909** be allocated by the cache. ^szPage will always a power of two. ^The
7910** second parameter szExtra is a number of bytes of extra storage
7911** associated with each page cache entry. ^The szExtra parameter will
7912** a number less than 250. SQLite will use the
7913** extra szExtra bytes on each page to store metadata about the underlying
7914** database page on disk. The value passed into szExtra depends
7915** on the SQLite version, the target platform, and how SQLite was compiled.
7916** ^The third argument to xCreate(), bPurgeable, is true if the cache being
7917** created will be used to cache database pages of a file stored on disk, or
7918** false if it is used for an in-memory database. The cache implementation
7919** does not have to do anything special based with the value of bPurgeable;
7920** it is purely advisory. ^On a cache where bPurgeable is false, SQLite will
7921** never invoke xUnpin() except to deliberately delete a page.
7922** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
7923** false will always have the "discard" flag set to true.
7924** ^Hence, a cache created with bPurgeable false will
7925** never contain any unpinned pages.
7927** [[the xCachesize() page cache method]]
7928** ^(The xCachesize() method may be called at any time by SQLite to set the
7929** suggested maximum cache-size (number of pages stored by) the cache
7930** instance passed as the first argument. This is the value configured using
7931** the SQLite "[PRAGMA cache_size]" command.)^ As with the bPurgeable
7932** parameter, the implementation is not required to do anything with this
7933** value; it is advisory only.
7935** [[the xPagecount() page cache methods]]
7936** The xPagecount() method must return the number of pages currently
7937** stored in the cache, both pinned and unpinned.
7939** [[the xFetch() page cache methods]]
7940** The xFetch() method locates a page in the cache and returns a pointer to
7941** an sqlite3_pcache_page object associated with that page, or a NULL pointer.
7942** The pBuf element of the returned sqlite3_pcache_page object will be a
7943** pointer to a buffer of szPage bytes used to store the content of a
7944** single database page. The pExtra element of sqlite3_pcache_page will be
7945** a pointer to the szExtra bytes of extra storage that SQLite has requested
7946** for each entry in the page cache.
7948** The page to be fetched is determined by the key. ^The minimum key value
7949** is 1. After it has been retrieved using xFetch, the page is considered
7950** to be "pinned".
7952** If the requested page is already in the page cache, then the page cache
7953** implementation must return a pointer to the page buffer with its content
7954** intact. If the requested page is not already in the cache, then the
7955** cache implementation should use the value of the createFlag
7956** parameter to help it determined what action to take:
7958** <table border=1 width=85% align=center>
7959** <tr><th> createFlag <th> Behavior when page is not already in cache
7960** <tr><td> 0 <td> Do not allocate a new page. Return NULL.
7961** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
7962** Otherwise return NULL.
7963** <tr><td> 2 <td> Make every effort to allocate a new page. Only return
7964** NULL if allocating a new page is effectively impossible.
7965** </table>
7967** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1. SQLite
7968** will only use a createFlag of 2 after a prior call with a createFlag of 1
7969** failed.)^ In between the to xFetch() calls, SQLite may
7970** attempt to unpin one or more cache pages by spilling the content of
7971** pinned pages to disk and synching the operating system disk cache.
7973** [[the xUnpin() page cache method]]
7974** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
7975** as its second argument. If the third parameter, discard, is non-zero,
7976** then the page must be evicted from the cache.
7977** ^If the discard parameter is
7978** zero, then the page may be discarded or retained at the discretion of
7979** page cache implementation. ^The page cache implementation
7980** may choose to evict unpinned pages at any time.
7982** The cache must not perform any reference counting. A single
7983** call to xUnpin() unpins the page regardless of the number of prior calls
7984** to xFetch().
7986** [[the xRekey() page cache methods]]
7987** The xRekey() method is used to change the key value associated with the
7988** page passed as the second argument. If the cache
7989** previously contains an entry associated with newKey, it must be
7990** discarded. ^Any prior cache entry associated with newKey is guaranteed not
7991** to be pinned.
7993** When SQLite calls the xTruncate() method, the cache must discard all
7994** existing cache entries with page numbers (keys) greater than or equal
7995** to the value of the iLimit parameter passed to xTruncate(). If any
7996** of these pages are pinned, they are implicitly unpinned, meaning that
7997** they can be safely discarded.
7999** [[the xDestroy() page cache method]]
8000** ^The xDestroy() method is used to delete a cache allocated by xCreate().
8001** All resources associated with the specified cache should be freed. ^After
8002** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
8003** handle invalid, and will not use it with any other sqlite3_pcache_methods2
8004** functions.
8006** [[the xShrink() page cache method]]
8007** ^SQLite invokes the xShrink() method when it wants the page cache to
8008** free up as much of heap memory as possible. The page cache implementation
8009** is not obligated to free any memory, but well-behaved implementations should
8010** do their best.
8012typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;
8013struct sqlite3_pcache_methods2 {
8014 int iVersion;
8015 void *pArg;
8016 int (*xInit)(void*);
8017 void (*xShutdown)(void*);
8018 sqlite3_pcache *(*xCreate)(int szPage, int szExtra, int bPurgeable);
8019 void (*xCachesize)(sqlite3_pcache*, int nCachesize);
8020 int (*xPagecount)(sqlite3_pcache*);
8021 sqlite3_pcache_page *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
8022 void (*xUnpin)(sqlite3_pcache*, sqlite3_pcache_page*, int discard);
8023 void (*xRekey)(sqlite3_pcache*, sqlite3_pcache_page*,
8024 unsigned oldKey, unsigned newKey);
8025 void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
8026 void (*xDestroy)(sqlite3_pcache*);
8027 void (*xShrink)(sqlite3_pcache*);
8031** This is the obsolete pcache_methods object that has now been replaced
8032** by sqlite3_pcache_methods2. This object is not used by SQLite. It is
8033** retained in the header file for backwards compatibility only.
8035typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
8036struct sqlite3_pcache_methods {
8037 void *pArg;
8038 int (*xInit)(void*);
8039 void (*xShutdown)(void*);
8040 sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
8041 void (*xCachesize)(sqlite3_pcache*, int nCachesize);
8042 int (*xPagecount)(sqlite3_pcache*);
8043 void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
8044 void (*xUnpin)(sqlite3_pcache*, void*, int discard);
8045 void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
8046 void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
8047 void (*xDestroy)(sqlite3_pcache*);
8052** CAPI3REF: Online Backup Object
8054** The sqlite3_backup object records state information about an ongoing
8055** online backup operation. ^The sqlite3_backup object is created by
8056** a call to [sqlite3_backup_init()] and is destroyed by a call to
8057** [sqlite3_backup_finish()].
8059** See Also: [Using the SQLite Online Backup API]
8061typedef struct sqlite3_backup sqlite3_backup;
8064** CAPI3REF: Online Backup API.
8066** The backup API copies the content of one database into another.
8067** It is useful either for creating backups of databases or
8068** for copying in-memory databases to or from persistent files.
8070** See Also: [Using the SQLite Online Backup API]
8072** ^SQLite holds a write transaction open on the destination database file
8073** for the duration of the backup operation.
8074** ^The source database is read-locked only while it is being read;
8075** it is not locked continuously for the entire backup operation.
8076** ^Thus, the backup may be performed on a live source database without
8077** preventing other database connections from
8078** reading or writing to the source database while the backup is underway.
8080** ^(To perform a backup operation:
8081** <ol>
8082** <li><b>sqlite3_backup_init()</b> is called once to initialize the
8083** backup,
8084** <li><b>sqlite3_backup_step()</b> is called one or more times to transfer
8085** the data between the two databases, and finally
8086** <li><b>sqlite3_backup_finish()</b> is called to release all resources
8087** associated with the backup operation.
8088** </ol>)^
8089** There should be exactly one call to sqlite3_backup_finish() for each
8090** successful call to sqlite3_backup_init().
8092** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
8094** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the
8095** [database connection] associated with the destination database
8096** and the database name, respectively.
8097** ^The database name is "main" for the main database, "temp" for the
8098** temporary database, or the name specified after the AS keyword in
8099** an [ATTACH] statement for an attached database.
8100** ^The S and M arguments passed to
8101** sqlite3_backup_init(D,N,S,M) identify the [database connection]
8102** and database name of the source database, respectively.
8103** ^The source and destination [database connections] (parameters S and D)
8104** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
8105** an error.
8107** ^A call to sqlite3_backup_init() will fail, returning NULL, if
8108** there is already a read or read-write transaction open on the
8109** destination database.
8111** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
8112** returned and an error code and error message are stored in the
8113** destination [database connection] D.
8114** ^The error code and message for the failed call to sqlite3_backup_init()
8115** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
8116** [sqlite3_errmsg16()] functions.
8117** ^A successful call to sqlite3_backup_init() returns a pointer to an
8118** [sqlite3_backup] object.
8119** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
8120** sqlite3_backup_finish() functions to perform the specified backup
8121** operation.
8123** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
8125** ^Function sqlite3_backup_step(B,N) will copy up to N pages between
8126** the source and destination databases specified by [sqlite3_backup] object B.
8127** ^If N is negative, all remaining source pages are copied.
8128** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
8129** are still more pages to be copied, then the function returns [SQLITE_OK].
8130** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
8131** from source to destination, then it returns [SQLITE_DONE].
8132** ^If an error occurs while running sqlite3_backup_step(B,N),
8133** then an [error code] is returned. ^As well as [SQLITE_OK] and
8134** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
8136** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
8138** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
8139** <ol>
8140** <li> the destination database was opened read-only, or
8141** <li> the destination database is using write-ahead-log journaling
8142** and the destination and source page sizes differ, or
8143** <li> the destination database is an in-memory database and the
8144** destination and source page sizes differ.
8145** </ol>)^
8147** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
8148** the [sqlite3_busy_handler | busy-handler function]
8149** is invoked (if one is specified). ^If the
8150** busy-handler returns non-zero before the lock is available, then
8151** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
8152** sqlite3_backup_step() can be retried later. ^If the source
8153** [database connection]
8154** is being used to write to the source database when sqlite3_backup_step()
8155** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
8156** case the call to sqlite3_backup_step() can be retried later on. ^(If
8158** [SQLITE_READONLY] is returned, then
8159** there is no point in retrying the call to sqlite3_backup_step(). These
8160** errors are considered fatal.)^ The application must accept
8161** that the backup operation has failed and pass the backup operation handle
8162** to the sqlite3_backup_finish() to release associated resources.
8164** ^The first call to sqlite3_backup_step() obtains an exclusive lock
8165** on the destination file. ^The exclusive lock is not released until either
8166** sqlite3_backup_finish() is called or the backup operation is complete
8167** and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to
8168** sqlite3_backup_step() obtains a [shared lock] on the source database that
8169** lasts for the duration of the sqlite3_backup_step() call.
8170** ^Because the source database is not locked between calls to
8171** sqlite3_backup_step(), the source database may be modified mid-way
8172** through the backup process. ^If the source database is modified by an
8173** external process or via a database connection other than the one being
8174** used by the backup operation, then the backup will be automatically
8175** restarted by the next call to sqlite3_backup_step(). ^If the source
8176** database is modified by the using the same database connection as is used
8177** by the backup operation, then the backup database is automatically
8178** updated at the same time.
8180** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
8182** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the
8183** application wishes to abandon the backup operation, the application
8184** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
8185** ^The sqlite3_backup_finish() interfaces releases all
8186** resources associated with the [sqlite3_backup] object.
8187** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
8188** active write-transaction on the destination database is rolled back.
8189** The [sqlite3_backup] object is invalid
8190** and may not be used following a call to sqlite3_backup_finish().
8192** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
8193** sqlite3_backup_step() errors occurred, regardless or whether or not
8194** sqlite3_backup_step() completed.
8195** ^If an out-of-memory condition or IO error occurred during any prior
8196** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
8197** sqlite3_backup_finish() returns the corresponding [error code].
8199** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
8200** is not a permanent error and does not affect the return value of
8201** sqlite3_backup_finish().
8203** [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]]
8204** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
8206** ^The sqlite3_backup_remaining() routine returns the number of pages still
8207** to be backed up at the conclusion of the most recent sqlite3_backup_step().
8208** ^The sqlite3_backup_pagecount() routine returns the total number of pages
8209** in the source database at the conclusion of the most recent
8210** sqlite3_backup_step().
8211** ^(The values returned by these functions are only updated by
8212** sqlite3_backup_step(). If the source database is modified in a way that
8213** changes the size of the source database or the number of pages remaining,
8214** those changes are not reflected in the output of sqlite3_backup_pagecount()
8215** and sqlite3_backup_remaining() until after the next
8216** sqlite3_backup_step().)^
8218** <b>Concurrent Usage of Database Handles</b>
8220** ^The source [database connection] may be used by the application for other
8221** purposes while a backup operation is underway or being initialized.
8222** ^If SQLite is compiled and configured to support threadsafe database
8223** connections, then the source database connection may be used concurrently
8224** from within other threads.
8226** However, the application must guarantee that the destination
8227** [database connection] is not passed to any other API (by any thread) after
8228** sqlite3_backup_init() is called and before the corresponding call to
8229** sqlite3_backup_finish(). SQLite does not currently check to see
8230** if the application incorrectly accesses the destination [database connection]
8231** and so no error code is reported, but the operations may malfunction
8232** nevertheless. Use of the destination database connection while a
8233** backup is in progress might also also cause a mutex deadlock.
8235** If running in [shared cache mode], the application must
8236** guarantee that the shared cache used by the destination database
8237** is not accessed while the backup is running. In practice this means
8238** that the application must guarantee that the disk file being
8239** backed up to is not accessed by any connection within the process,
8240** not just the specific connection that was passed to sqlite3_backup_init().
8242** The [sqlite3_backup] object itself is partially threadsafe. Multiple
8243** threads may safely make multiple concurrent calls to sqlite3_backup_step().
8244** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
8245** APIs are not strictly speaking threadsafe. If they are invoked at the
8246** same time as another thread is invoking sqlite3_backup_step() it is
8247** possible that they return invalid values.
8249SQLITE_API sqlite3_backup *sqlite3_backup_init(
8250 sqlite3 *pDest, /* Destination database handle */
8251 const char *zDestName, /* Destination database name */
8252 sqlite3 *pSource, /* Source database handle */
8253 const char *zSourceName /* Source database name */
8255SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
8256SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
8257SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
8258SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
8261** CAPI3REF: Unlock Notification
8262** METHOD: sqlite3
8264** ^When running in shared-cache mode, a database operation may fail with
8265** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
8266** individual tables within the shared-cache cannot be obtained. See
8267** [SQLite Shared-Cache Mode] for a description of shared-cache locking.
8268** ^This API may be used to register a callback that SQLite will invoke
8269** when the connection currently holding the required lock relinquishes it.
8270** ^This API is only available if the library was compiled with the
8271** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
8273** See Also: [Using the SQLite Unlock Notification Feature].
8275** ^Shared-cache locks are released when a database connection concludes
8276** its current transaction, either by committing it or rolling it back.
8278** ^When a connection (known as the blocked connection) fails to obtain a
8279** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
8280** identity of the database connection (the blocking connection) that
8281** has locked the required resource is stored internally. ^After an
8282** application receives an SQLITE_LOCKED error, it may call the
8283** sqlite3_unlock_notify() method with the blocked connection handle as
8284** the first argument to register for a callback that will be invoked
8285** when the blocking connections current transaction is concluded. ^The
8286** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
8287** call that concludes the blocking connections transaction.
8289** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
8290** there is a chance that the blocking connection will have already
8291** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
8292** If this happens, then the specified callback is invoked immediately,
8293** from within the call to sqlite3_unlock_notify().)^
8295** ^If the blocked connection is attempting to obtain a write-lock on a
8296** shared-cache table, and more than one other connection currently holds
8297** a read-lock on the same table, then SQLite arbitrarily selects one of
8298** the other connections to use as the blocking connection.
8300** ^(There may be at most one unlock-notify callback registered by a
8301** blocked connection. If sqlite3_unlock_notify() is called when the
8302** blocked connection already has a registered unlock-notify callback,
8303** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
8304** called with a NULL pointer as its second argument, then any existing
8305** unlock-notify callback is canceled. ^The blocked connections
8306** unlock-notify callback may also be canceled by closing the blocked
8307** connection using [sqlite3_close()].
8309** The unlock-notify callback is not reentrant. If an application invokes
8310** any sqlite3_xxx API functions from within an unlock-notify callback, a
8311** crash or deadlock may be the result.
8313** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
8314** returns SQLITE_OK.
8316** <b>Callback Invocation Details</b>
8318** When an unlock-notify callback is registered, the application provides a