yii2中事务不能回滚的解决

$player1 = Player::findOne(1);
$player1->nickname = '111';
$player2 = Player::findOne(2);
$player2->nickname = '222';
$transaction = Yii::$app->db->beginTransaction();
if ($player1->validate() && $player2->validate()) {
    try {
        $player1->save();
        $player2->save();
        $transaction->commit();
    } catch (Exception $e) {
        $transaction->rollback();
    }
}else{
    var_dump($player1->errors);
    var_dump($player2->errors);
}