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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(). An sqlite3* handle is usually returned in *ppDb, even if an error occurs. The only exception is 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.

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 sqlite3* 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 acccepts two additional parameters for additional control over the new database connection. The flags parameter can be one of:

1. SQLITE_OPEN_READONLY
2. SQLITE_OPEN_READWRITE
3. SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE

The first value opens the database read-only. If the database does not previously exist, an error is returned. The second option opens the database for reading and writing if possible, or reading only if if the file is write protected. In either case the database must already exist or an error is returned. The third option opens the database for reading and writing and creates it if it does not already exist. The third options is behavior that is always used for sqlite3_open() and sqlite3_open16().

If the filename is ":memory:", then an private in-memory database is created for the connection. This in-memory database will vanish when the database connection is closed. Future version of SQLite might make use of additional special filenames that begin with the ":" character. It is recommended that when a database filename really does begin with ":" that you prefix the filename with a pathname like "./" 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().

### Invariants:

F12701 | The sqlite3_open(), sqlite3_open16(), and sqlite3_open_v2() interfaces create a new database connection associated with the database file given in their first parameter.
F12702 | 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().
F12703 | A successful invocation of sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2() writes a pointer to a new database connection into *ppDb.
F12704 | The sqlite3_open(), sqlite3_open16(), and sqlite3_open_v2() interfaces return SQLITE_OK upon success, or an appropriate error code on failure.
F12706 | The default text encoding for a new database created using sqlite3_open() or sqlite3_open_v2() will be UTF-8.
F12707 | The default text encoding for a new database created using sqlite3_open16() will be UTF-16.
F12709 | The sqlite3_open(F,D) interface is equivalent to sqlite3_open_v2(F,D,G,0) where the G parameter is SQLITE_OPEN_READWRITE| SQLITE_OPEN_CREATE.
F12711 | If the G parameter to sqlite3_open_v2(F,D,G,V) contains the bit value SQLITE_OPEN_READONLY then the database is opened for reading only.
F12712 | If the G parameter to sqlite3_open_v2(F,D,G,V) contains the bit value SQLITE_OPEN_READWRITE then the database is opened reading and writing if possible, or for reading only if the file is write protected by the operating system.
F12713 | If the G parameter to sqlite3_open(v2(F,D,G,V) omits the bit value SQLITE_OPEN_CREATE and the database does not previously exist, an error is returned.
F12714 | If the G parameter to sqlite3_open(v2(F,D,G,V) contains the bit value SQLITE_OPEN_CREATE and the database does not previously exist, then an attempt is made to create and initialize the database.
F12717 | If the filename argument to sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2() is ":memory:", then an private, ephemeral, in-memory database is created for the connection. (TODO: Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required in sqlite3_open_v2()?)
F12719 | If the filename is an empty string, then a private, ephermeral on-disk database will be created. (TODO: Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required in sqlite3_open_v2()?)
F12721 | The database connection created by sqlite3_open_v2(F,D,G,V) will use the sqlite3_vfs object identified by the V parameter, or the default sqlite3_vfs object is V is a NULL pointer.

See also lists of Objects, Constants, and Functions.

This page last modified 2008/01/31 20:37:13 UTC