const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
^The sqlite3_db_filename(D,N) interface returns a pointer to a filename associated with database N of connection D. ^The main database file has the name "main". If there is no attached database N on the database connection D, or if database N is a temporary or in-memory database, then a NULL pointer is returned.
^The filename returned by this function is the output of the xFullPathname method of the VFS. ^In other words, the filename will be an absolute pathname, even if the filename used to open the database originally was a URI or relative pathname.