//create databaseNSString* dbPath =[(NSArray*)NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];dbPath =[dbPath stringByAppendingPathComponent:@"test.db"];db =[FMDatabase databaseWithPath:dbPath];if([db open]){
    NSLog(@"Database %@ opened", dbPath);//check for foreign_keyNSString* sql =@"PRAGMA foreign_keys";FMResultSet*rs =[db executeQuery:sql];int enabled;if([rs next]){
            enabled =[rs intForColumnIndex:0];}[rs close];if(!enabled){
    // enable foreign_key        sql =@"PRAGMA foreign_keys = ON;";[db executeUpdate:sql];// check if successful        sql =@"PRAGMA foreign_keys";FMResultSet*rs =[db executeQuery:sql];if([rs next]){
                enabled =[rs intForColumnIndex:0];}[rs close];}// do your stuff here, or just cache the connection}else{
    NSLog(@"Failed to open %@", dbPath);}