mysqli->error: Is it for the last query only, or for the last error from the query group?

Question

I am new to mysqli, and trying to confirm that if I so something like the below, the errno will be set to the last error, if any, and not the error of the last query.

Is this a decent practice or should I be checking for the error in between every query?

Thanks!

$mysqli->autocommit(FALSE);

$mysqli->query("INSERT INTO .....");
$mysqli->query("INSERT INTO .....");
$mysqli->query("INSERT INTO .....");
$mysqli->query("INSERT INTO .....");
$mysqli->query("INSERT INTO .....");

if ( 0==$mysqli->errno ) {
    $mysqli->commit();
} else {
    $mysqli->rollback();
    // Handle error
}

Answer 1

mysqli_errno — Returns the error code for the most recent function call.

Answer 2

No -- it reports the error code of the last mysqli function call. Zero means no error occurred on the last function call. So if one in the middle fails, you won't know about it by checking only at the end.

In other words, yes, you need to check the error code after each function call. Note that an error is indicated by the return value of $mysqli->query() as well. Paraphrasing the example from the mysqli_errno doc:

if (!$mysqli->query("INSERT ...")) {
    printf("Errorcode: %d\n", $mysqli->errno);
}

Answer 3

No you have to check in between every query because it will always give you error for last query only... So if your first query failed and last execute properly then you will not get error... so check after all query one by one not at last...

Answer 4

IMO the best way and easiest way to catch all errors is to extend the mysqli class:

class DBException extends Exception {
}
class DBConnectException extends DBException {
}
class DBQueryException extends DBException {
}

class DB extends MySQLi {
    private static $instance = null;

    private function __construct() {
        parent::__construct('host',
                            'username',
                            'passwd',
                            'dbname');

        if ($this->connect_errno) {
            throw new DBConnectException($this->connect_error, $this->connect_errno);
        }
    }

    private function __destructor() {
        parent::close();
    }

    private function __clone() {
    }

    public static function getInstance() {
        if (self::$instance == null) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    public function query($query, $resultmode = MYSQLI_STORE_RESULT) {
        $result = parent::query($query, $resultmode);
        if (!$result) {
            // or do whatever you wanna do when an error occurs
            throw new DBQueryException($this->error, $this->errno);
        }
        return $result;
    }
}