Как правильно сделать клон базы?

$bd = Yii::$app->getDb();
        $result = $bd->createCommand(`mysqldump -u root -p1234 db1 | mysql -u root -p1234 db2`)->queryScalar();
        echo '<pre>';
        print_r($result);
        echo '</pre>';
        return 'end';

SQLSTATE[42000]: Syntax error or access violation: 1065 Query was empty
The SQL being executed was:
Error Info: Array
(
    [0] => 42000
    [1] => 1065
    [2] => Query was empty

shell_exec ( 'mysqldump -u root -p1234 db1 | mysql -u root -p1234 db2' );