sqlite3.h

sqllive C开发的轻量级的数据库。 对想深入了解数据库的数据结构有很好的借鉴

** <li> [SQLITE_IOCAP_ATOMIC512]
** <li> [SQLITE_IOCAP_ATOMIC1K]
** <li> [SQLITE_IOCAP_ATOMIC2K]
** <li> [SQLITE_IOCAP_ATOMIC4K]
** <li> [SQLITE_IOCAP_ATOMIC8K]
** <li> [SQLITE_IOCAP_ATOMIC16K]
** <li> [SQLITE_IOCAP_ATOMIC32K]
** <li> [SQLITE_IOCAP_ATOMIC64K]
** <li> [SQLITE_IOCAP_SAFE_APPEND]
** <li> [SQLITE_IOCAP_SEQUENTIAL]
** </ul>
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
*/
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
  int iVersion;
  int (*xClose)(sqlite3_file*);
  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*);
  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
  int (*xSectorSize)(sqlite3_file*);
  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Standard File Control Opcodes {F11310}
**
** These integer constants are opcodes for the xFileControl method
** of the [sqlite3_io_methods] object and to the [sqlite3_file_control()]
** interface.
**
** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
** opcode causes the xFileControl method to write the current state of
** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
** into an integer that the pArg argument points to. This capability
** is used during testing and only needs to be supported when SQLITE_TEST
** is defined.
*/
#define SQLITE_FCNTL_LOCKSTATE        1

/*
** CAPI3REF: Mutex Handle {F17110}
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
** deals with pointers to the [sqlite3_mutex] object.
**
** Mutexes are created using [sqlite3_mutex_alloc()].
*/
typedef struct sqlite3_mutex sqlite3_mutex;

/*
** CAPI3REF: OS Interface Object {F11140}
**
** An instance of this object defines the interface between the
** SQLite core and the underlying operating system.  The "vfs"
** in the name of the object stands for "virtual file system".
**
** The iVersion field is initially 1 but may be larger for future
** versions of SQLite.  Additional fields may be appended to this
** object when the iVersion value is increased.
**
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS.  mxPathname is the maximum length of
** a pathname in this VFS.
**
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer.  The [sqlite3_vfs_register()]
** and [sqlite3_vfs_unregister()] interfaces manage this list
** in a thread-safe way.  The [sqlite3_vfs_find()] interface
** searches the list.
**
** The pNext field is the only field in the sqlite3_vfs 
** structure that SQLite will ever modify.  SQLite will only access
** or modify this field while holding a particular static mutex.
** The application should never modify anything within the sqlite3_vfs
** object once the object has been registered.
**
** The zName field holds the name of the VFS module.  The name must
** be unique across all VFS modules.
**
** {F11141} SQLite will guarantee that the zFilename string passed to
** xOpen() is a full pathname as generated by xFullPathname() and
** that the string will be valid and unchanged until xClose() is
** called.  {END} So the [sqlite3_file] can store a pointer to the
** filename if it needs to remember the filename for some reason.
**
** {F11142} The flags argument to xOpen() includes all bits set in
** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
** or [sqlite3_open16()] is used, then flags includes at least
** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. {END}
** If xOpen() opens a file read-only then it sets *pOutFlags to
** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be
** set.
** 
** {F11143} SQLite will also add one of the following flags to the xOpen()
** call, depending on the object being opened:
** 
** <ul>
** <li>  [SQLITE_OPEN_MAIN_DB]
** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
** <li>  [SQLITE_OPEN_TEMP_DB]
** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
** <li>  [SQLITE_OPEN_TRANSIENT_DB]
** <li>  [SQLITE_OPEN_SUBJOURNAL]
** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
** </ul> {END}
**
** The file I/O implementation can use the object type flags to
** changes the way it deals with files.  For example, an application
** that does not care about crash recovery or rollback might make
** the open of a journal file a no-op.  Writes to this journal would
** also be no-ops, and any attempt to read the journal would return 
** SQLITE_IOERR.  Or the implementation might recognize that a database 
** file will be doing page-aligned sector reads and writes in a random 
** order and set up its I/O subsystem accordingly.
** 
** SQLite might also add one of the following flags to the xOpen
** method:
** 
** <ul>
** <li> [SQLITE_OPEN_DELETEONCLOSE]
** <li> [SQLITE_OPEN_EXCLUSIVE]
** </ul>
** 
** {F11145} The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
** deleted when it is closed.  {F11146} The [SQLITE_OPEN_DELETEONCLOSE]
** will be set for TEMP  databases, journals and for subjournals. 
** {F11147} The [SQLITE_OPEN_EXCLUSIVE] flag means the file should be opened
** for exclusive access.  This flag is set for all files except
** for the main database file. {END}
** 
** {F11148} At least szOsFile bytes of memory are allocated by SQLite 
** to hold the  [sqlite3_file] structure passed as the third 
** argument to xOpen.  {END}  The xOpen method does not have to
** allocate the structure; it should just fill it in.
** 
** {F11149} The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS] 
** to test for the existance of a file,
** or [SQLITE_ACCESS_READWRITE] to test to see
** if a file is readable and writable, or [SQLITE_ACCESS_READ]
** to test to see if a file is at least readable.  {END} The file can be a 
** directory.
** 
** {F11150} SQLite will always allocate at least mxPathname+1 bytes for
** the output buffers for xGetTempname and xFullPathname. {F11151} The exact
** size of the output buffer is also passed as a parameter to both 
** methods. {END} If the output buffer is not large enough, SQLITE_CANTOPEN
** should be returned. As this is handled as a fatal error by SQLite,
** vfs implementations should endeavor to prevent this by setting 
** mxPathname to a sufficiently large value.
** 
** The xRandomness(), xSleep(), and xCurrentTime() interfaces
** are not strictly a part of the filesystem, but they are
** included in the VFS structure for completeness.
** The xRandomness() function attempts to return nBytes bytes
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.  The
** xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  The xCurrentTime()
** method returns a Julian Day Number for the current date and
** time.
*/
typedef struct sqlite3_vfs sqlite3_vfs;
struct sqlite3_vfs {
  int iVersion;            /* Structure version number */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Pointer to application-specific data */
  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags);
  int (*xGetTempname)(sqlite3_vfs*, int nOut, char *zOut);
  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  void *(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol);
  void (*xDlClose)(sqlite3_vfs*, void*);
  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  int (*xSleep)(sqlite3_vfs*, int microseconds);
  int (*xCurrentTime)(sqlite3_vfs*, double*);
  /* New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. */
};

/*
** CAPI3REF: Flags for the xAccess VFS method {F11190}
**
** {F11191} These integer constants can be used as the third parameter to
** the xAccess method of an [sqlite3_vfs] object. {END}  They determine
** what kind of permissions the xAccess method is
** looking for.  {F11192} With SQLITE_ACCESS_EXISTS, the xAccess method
** simply checks to see if the file exists. {F11193} With
** SQLITE_ACCESS_READWRITE, the xAccess method checks to see
** if the file is both readable and writable.  {F11194} With
** SQLITE_ACCESS_READ the xAccess method
** checks to see if the file is readable.
*/
#define SQLITE_ACCESS_EXISTS    0
#define SQLITE_ACCESS_READWRITE 1
#define SQLITE_ACCESS_READ      2

/*
** CAPI3REF: Enable Or Disable Extended Result Codes {F12200}
**
** The sqlite3_extended_result_codes() routine enables or disables the
** [SQLITE_IOERR_READ | extended result codes] feature of SQLite.
** The extended result codes are disabled by default for historical
** compatibility.
**
** INVARIANTS:
**
** {F12201} Each new [database connection] has the 
**          [extended result codes] feature
**          disabled by default.
**
** {F12202} The [sqlite3_extended_result_codes(D,F)] interface will enable
**          [extended result codes] for the 
**          [database connection] D if the F parameter
**          is true, or disable them if F is false.
*/
int sqlite3_extended_result_codes(sqlite3*, int onoff);

/*
** CAPI3REF: Last Insert Rowid {F12220}
**
** Each entry in an SQLite table has a unique 64-bit signed
** integer key called the "rowid". The rowid is always available
** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
** names are not also used by explicitly declared columns. If
** the table has a column of type INTEGER PRIMARY KEY then that column
** is another alias for the rowid.
**
** This routine returns the rowid of the most recent
** successful INSERT into the database from the database connection
** shown in the first argument.  If no successful inserts
** have ever occurred on this database connection, zero is returned.
**
** If an INSERT occurs within a trigger, then the rowid of the
** inserted row is returned by this routine as long as the trigger
** is running.  But once the trigger terminates, the value returned
** by this routine reverts to the last value inserted before the
** trigger fired.
**
** An INSERT that fails due to a constraint violation is not a
** successful insert and does not change the value returned by this
** routine.  Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
** and INSERT OR ABORT make no changes to the return value of this
** routine when their insertion fails.  When INSERT OR REPLACE 
** encounters a constraint violation, it does not fail.  The
** INSERT continues to completion after deleting rows that caused
** the constraint problem so INSERT OR REPLACE will always change
** the return value of this interface. 
**
** For the purposes of this routine, an insert is considered to
** be successful even if it is subsequently rolled back.
**
** INVARIANTS:
**
** {F12221} The [sqlite3_last_insert_rowid()] function returns the
**          rowid of the most recent successful insert done
**          on the same database connection and within the same
**          trigger context, or zero if there have
**          been no qualifying inserts on that connection.
**
** {F12223} The [sqlite3_last_insert_rowid()] function returns
**          same value when called from the same trigger context
**          immediately before and after a ROLLBACK.
**
** LIMITATIONS:
**
** {U12232} If a separate thread does a new insert on the same
**          database connection while the [sqlite3_last_insert_rowid()]
**          function is running and thus changes the last insert rowid,
**          then the value returned by [sqlite3_last_insert_rowid()] is
**          unpredictable and might not equal either the old or the new
**          last insert rowid.
*/
sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);