yii2.0 事务

//创建事务
        $tr = Yii::$app->db->beginTransaction();
        try {
            for($i=1;$i<=3;$i++){
                $test = new Areas();
                $test->name = 'name'.$i;
                $test->sort=1;
                if($test->save()){
                    echo "save $i | ";
                }

            }
            $test = new Areas();
            $test->name = 'ab'.$i;
            $test->sorta=1; //写入不存在的字段
            if(!$test->save()){
                "save fail"; //如果没有写入就输出
            }
            //提交
            $tr->commit();
        } catch (Exception $e) {
            //回滚
            $tr->rollBack();
            echo  "rollback";
        }