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## SQLite C Interface

## Opening A New Database Connection

>     int sqlite3_open(
>       const char *filename,   /* Database filename (UTF-8) */
>       sqlite3 **ppDb          /* OUT: SQLite db handle */
>     );
>     int sqlite3_open16(
>       const void *filename,   /* Database filename (UTF-16) */
>       sqlite3 **ppDb          /* OUT: SQLite db handle */
>     );
>     int sqlite3_open_v2(
>       const char *filename,   /* Database filename (UTF-8) */
>       sqlite3 **ppDb,         /* OUT: SQLite db handle */
>       int flags,              /* Flags */
>       const char *zVfs        /* Name of VFS module to use */
>     );

These routines open an SQLite database file whose name is given by the filename argument. The filename argument is interpreted as UTF-8 for sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte order for sqlite3_open16(). A database connection handle is usually returned in *ppDb, even if an error occurs. The only exception is that if SQLite is unable to allocate memory to hold the sqlite3 object, a NULL will be written into *ppDb instead of a pointer to the sqlite3 object. If the database is opened (and/or created) successfully, then SQLITE_OK is returned. Otherwise an error code is returned. The sqlite3_errmsg() or sqlite3_errmsg16() routines can be used to obtain an English language description of the error following a failure of any of the sqlite3_open() routines.

The default encoding for the database will be UTF-8 if sqlite3_open() or sqlite3_open_v2() is called and UTF-16 in the native byte order if sqlite3_open16() is used.

Whether or not an error occurs when it is opened, resources associated with the database connection handle should be released by passing it to sqlite3_close() when it is no longer required.

The sqlite3_open_v2() interface works like sqlite3_open() except that it accepts two additional parameters for additional control over the new database connection. The flags parameter to sqlite3_open_v2() can take one of the following three values, optionally combined with the SQLITE_OPEN_NOMUTEX, SQLITE_OPEN_FULLMUTEX, SQLITE_OPEN_SHAREDCACHE, and/or SQLITE_OPEN_PRIVATECACHE flags:

SQLITE_OPEN_READONLY
  The database is opened in read-only mode. If the database does not already exist, an error is returned.

SQLITE_OPEN_READWRITE
  The database is opened for reading and writing if possible, or reading only if the file is write protected by the operating system. In either case the database must already exist, otherwise an error is returned.

SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
  The database is opened for reading and writing, and is creates it if it does not already exist. This is the behavior that is always used for sqlite3_open() and sqlite3_open16().

If the 3rd parameter to sqlite3_open_v2() is not one of the combinations shown above or one of the combinations shown above combined with the SQLITE_OPEN_NOMUTEX, SQLITE_OPEN_FULLMUTEX, SQLITE_OPEN_SHAREDCACHE and/or SQLITE_OPEN_PRIVATECACHE flags, then the behavior is undefined.

If the SQLITE_OPEN_NOMUTEX flag is set, then the database connection opens in the multi-thread threading mode as long as the single-thread mode has not been set at compile-time or start-time. If the SQLITE_OPEN_FULLMUTEX flag is set then the database connection opens in the serialized threading mode unless single-thread was previously selected at compile-time or start-time. The SQLITE_OPEN_SHAREDCACHE flag causes the database connection to be eligible to use shared cache mode, regardless of whether or not shared cache is enabled using sqlite3_enable_shared_cache(). The SQLITE_OPEN_PRIVATECACHE flag causes the database connection to not participate in shared cache mode even if it is enabled.

If the filename is ":memory:", then a private, temporary in-memory database is created for the connection. This in-memory database will vanish when the database connection is closed. Future versions of SQLite might make use of additional special filenames that begin with the ":" character. It is recommended that when a database filename actually does begin with a ":" character you should prefix the filename with a pathname such as "./" to avoid ambiguity.

If the filename is an empty string, then a private, temporary on-disk database will be created. This private database will be automatically deleted as soon as the database connection is closed.

The fourth parameter to sqlite3_open_v2() is the name of the sqlite3_vfs object that defines the operating system interface that the new database connection should use. If the fourth parameter is a NULL pointer then the default sqlite3_vfs object is used.

Note to Windows users: The encoding used for the filename argument of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever codepage is currently defined. Filenames containing international characters must be converted to UTF-8 prior to passing them into sqlite3_open() or sqlite3_open_v2().

See also lists of Objects, Constants, and Functions.

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