SQLite

**
** 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],
** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
**
** <dl>
** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
** <dd>The database is opened in read-only mode.  If the database does not
** already exist, an error is returned.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
** <dd>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.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
** <dd>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().</dd>)^
** </dl>
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above optionally combined with other

** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
** 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

** 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 in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^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
** is set in the fourth 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.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** intepretation 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:").
**
** [[core URI query parameters]]
** The query component of a URI may contain parameters that are interpreted
** either by SQLite itself, or by a [VFS | custom VFS implementation].
** SQLite interprets the following three query parameters:
**
** <ul>
**   <li> <b>vfs</b>: ^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

**     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 behaviour requested by setting
**     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
** </ul>
**
** ^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]] <h3>URI filename examples</h3>
**
** <table border="1" align=center cellpadding=5>
** <tr><th> URI filenames <th> Results
** <tr><td> file:data.db <td> 
**          Open the file "data.db" in the current directory.
** <tr><td> file:/home/fred/data.db<br>
**          file:///home/fred/data.db <br>