Updated: 2022/Sep/29
Please read Privacy Policy. It's for your privacy.
SQLITE3_OPEN(3) Library Functions Manual SQLITE3_OPEN(3)
NAME
sqlite3_open, sqlite3_open16, sqlite3_open_v2 - opening a new database
connection
SYNOPSIS
#include <sqlite3.h>
int
sqlite3_open(const char *filename, sqlite3 **ppDb);
int
sqlite3_open16(const void *filename, sqlite3 **ppDb);
int
sqlite3_open_v2(const char *filename, sqlite3 **ppDb, int flags,
const char *zVfs);
DESCRIPTION
These routines open an SQLite database file as specified 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 will be UTF-8 for databases created using
sqlite3_open() or sqlite3_open_v2(). The default encoding for databases
created using sqlite3_open16() will be UTF-16 in the native byte order.
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() must
include, at a minimum, one of the following three flag combinations:
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. For historical reasons, if
opening in read-write mode fails due to OS-level permissions, an
attempt is made to open it in read-only mode.
sqlite3_db_readonly() can be used to determine whether the
database is actually read-write.
SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
The database is opened for reading and writing, and is created if
it does not already exist. This is the behavior that is always
used for sqlite3_open() and sqlite3_open16().
In addition to the required flags, the following optional flags are also
supported:
SQLITE_OPEN_URI
The filename can be interpreted as a URI if this flag is set.
SQLITE_OPEN_MEMORY
The database will be opened as an in-memory database. The
database is named by the "filename" argument for the purposes of
cache-sharing, if shared cache mode is enabled, but the
"filename" is otherwise ignored.
SQLITE_OPEN_NOMUTEX
The new database connection will use the "multi-thread" threading
mode. This means that separate threads are allowed to use SQLite
at the same time, as long as each thread is using a different
database connection.
SQLITE_OPEN_FULLMUTEX
The new database connection will use the "serialized" threading
mode. This means the multiple threads can safely attempt to use
the same database connection at the same time. (Mutexes will
block any actual concurrency, but in this mode there is no harm
in trying.)
SQLITE_OPEN_SHAREDCACHE
The database is opened shared cache enabled, overriding the
default shared cache setting provided by
sqlite3_enable_shared_cache(). The use of shared cache mode is
discouraged and hence shared cache capabilities may be omitted
from many builds of SQLite. In such cases, this option is a no-
op.
SQLITE_OPEN_PRIVATECACHE
The database is opened shared cache disabled, overriding the
default shared cache setting provided by
sqlite3_enable_shared_cache().
SQLITE_OPEN_EXRESCODE
The database connection comes up in "extended result code mode".
In other words, the database behaves has if
sqlite3_extended_result_codes(db,1) where called on the database
connection as soon as the connection is created. In addition to
setting the extended result code mode, this flag also causes
sqlite3_open_v2() to return an extended result code.
SQLITE_OPEN_NOFOLLOW
The database filename is not allowed to contain a symbolic link
If the 3rd parameter to sqlite3_open_v2() is not one of the required
combinations shown above optionally combined with other SQLITE_OPEN_*
bits then the behavior is undefined. Historic versions of SQLite have
silently ignored surplus bits in the flags parameter to
sqlite3_open_v2(), however that behavior might not be carried through
into future versions of SQLite and so applications should not rely upon
it. Note in particular that the SQLITE_OPEN_EXCLUSIVE flag is a no-op
for sqlite3_open_v2(). The SQLITE_OPEN_EXCLUSIVE does *not* cause the
open to fail if the database already exists. The SQLITE_OPEN_EXCLUSIVE
flag is intended for use by the VFS interface only, and not by
sqlite3_open_v2().
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.
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.
URI Filenames
If URI filename interpretation is enabled, and the filename argument
begins with "file:", then the filename is interpreted as a URI. URI
filename interpretation is enabled if the SQLITE_OPEN_URI flag is set in
the third argument to sqlite3_open_v2(), or if it has been enabled
globally using the SQLITE_CONFIG_URI option with the sqlite3_config()
method or by the SQLITE_USE_URI compile-time option. URI filename
interpretation is turned off by default, but future releases of SQLite
might enable URI filename interpretation by default. See "URI filenames"
for additional information.
URI filenames are parsed according to RFC 3986. If the URI contains an
authority, then it must be either an empty string or the string
"localhost". If the authority is not an empty string or "localhost", an
error is returned to the caller. The fragment component of a URI, if
present, is ignored.
SQLite uses the path component of the URI as the name of the disk file
which contains the database. If the path begins with a '/' character,
then it is interpreted as an absolute path. If the path does not begin
with a '/' (meaning that the authority section is omitted from the URI)
then the path is interpreted as a relative path. On windows, the first
component of an absolute path is a drive specification (e.g. "C:").
The query component of a URI may contain parameters that are interpreted
either by SQLite itself, or by a custom VFS implementation. SQLite and
its built-in VFSes interpret the following query parameters:
⊕ vfs: The "vfs" parameter may be used to specify the name of a VFS
object that provides the operating system interface that should be
used to access the database file on disk. If this option is set to
an empty string the default VFS object is used. Specifying an
unknown VFS is an error. If sqlite3_open_v2() is used and the vfs
option is present, then the VFS specified by the option takes
precedence over the value passed as the fourth parameter to
sqlite3_open_v2().
⊕ mode: The mode parameter may be set to either "ro", "rw", "rwc", or
"memory". Attempting to set it to any other value is an error. If
"ro" is specified, then the database is opened for read-only access,
just as if the SQLITE_OPEN_READONLY flag had been set in the third
argument to sqlite3_open_v2(). If the mode option is set to "rw",
then the database is opened for read-write (but not create) access,
as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had been
set. Value "rwc" is equivalent to setting both SQLITE_OPEN_READWRITE
and SQLITE_OPEN_CREATE. If the mode option is set to "memory" then a
pure in-memory database that never reads or writes from disk is used.
It is an error to specify a value for the mode parameter that is less
restrictive than that specified by the flags passed in the third
parameter to sqlite3_open_v2().
⊕ cache: The cache parameter may be set to either "shared" or
"private". Setting it to "shared" is equivalent to setting the
SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
sqlite3_open_v2(). Setting the cache parameter to "private" is
equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit. If
sqlite3_open_v2() is used and the "cache" parameter is present in a
URI filename, its value overrides any behavior requested by setting
SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
⊕ psow: The psow parameter indicates whether or not the powersafe
overwrite property does or does not apply to the storage media on
which the database file resides.
⊕ nolock: The nolock parameter is a boolean query parameter which if
set disables file locking in rollback journal modes. This is useful
for accessing a database on a filesystem that does not support
locking. Caution: Database corruption might result if two or more
processes write to the same database and any one of those processes
uses nolock=1.
⊕ immutable: The immutable parameter is a boolean query parameter that
indicates that the database file is stored on read-only media. When
immutable is set, SQLite assumes that the database file cannot be
changed, even by a process with higher privilege, and so the database
is opened read-only and all locking and change detection is disabled.
Caution: Setting the immutable property on a database file that does
in fact change can result in incorrect query results and/or
SQLITE_CORRUPT errors.
Specifying an unknown parameter in the query component of a URI is not an
error. Future versions of SQLite might understand additional query
parameters. See "query parameters with special meaning to SQLite" for
additional information.
URI filename examples
URI filenames Results
file:data.db Open the file "data.db" in the current directory.
file:/home/fred/data.db file:///home/fred/data.db
file://localhost/home/fred/data.db
Open the database file "/home/fred/data.db".
file://darkstar/home/fred/data.db An error. "darkstar" is not a
recognized authority.
file:///C:/Documents%20and%20Settings/fred/Desktop/data.db Windows
only: Open the file "data.db" on fred's desktop on drive C:. Note that
the %20 escaping in this example is not strictly necessary - space
characters can be used literally in URI filenames.
file:data.db?mode=ro&cache=private Open file "data.db" in the
current directory for read-only access. Regardless of whether or not
shared-cache mode is enabled by default, use a private cache.
file:/home/fred/data.db?vfs=unix-dotfile Open file
"/home/fred/data.db". Use the special VFS "unix-dotfile" that uses dot-
files in place of posix advisory locking.
file:data.db?mode=readonly An error. "readonly" is not a valid
option for the "mode" parameter. Use "ro" instead:
"file:data.db?mode=ro".
URI hexadecimal escape sequences (%HH) are supported within the path and
query components of a URI. A hexadecimal escape sequence consists of a
percent sign - "%" - followed by exactly two hexadecimal digits
specifying an octet value. Before the path or query components of a URI
filename are interpreted, they are encoded using UTF-8 and all
hexadecimal escape sequences replaced by a single byte containing the
corresponding octet. If this process generates an invalid UTF-8
encoding, the results are undefined.
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().
Note to Windows Runtime users: The temporary directory must be set prior
to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various
features that require the use of temporary files may fail.
IMPLEMENTATION NOTES
These declarations were extracted from the interface documentation at
line 3462.
SQLITE_API int sqlite3_open(
const char *filename, /* Database filename (UTF-8) */
sqlite3 **ppDb /* OUT: SQLite db handle */
);
SQLITE_API int sqlite3_open16(
const void *filename, /* Database filename (UTF-16) */
sqlite3 **ppDb /* OUT: SQLite db handle */
);
SQLITE_API 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 */
);
SEE ALSO
sqlite3(3), sqlite3_close(3), sqlite3_config(3), sqlite3_db_readonly(3),
sqlite3_enable_shared_cache(3), sqlite3_errcode(3),
sqlite3_temp_directory(3), sqlite3_vfs(3), SQLITE_CONFIG_SINGLETHREAD(3),
SQLITE_IOCAP_ATOMIC(3), SQLITE_OK(3), SQLITE_OPEN_READONLY(3)
NetBSD 10.99 August 24, 2023 NetBSD 10.99