查询：

$sql = "select * from ym_video where id=$id";

\YII::$app->db->createCommand($sql)->queryOne();     //查询一条语句

\YII::$app->db->createCommand($sql)->queryAll();     //查询全部语句

增删改：

// INSERT (table name, column values)
        Yii::$app->db->createCommand()->insert('user', [
            'name' => 'Sam',
            'age' => 30,
        ])->execute();

// UPDATE (table name, column values, condition)
        Yii::$app->db->createCommand()->update('user', ['status' => 1], 'age > 30')->execute();

// DELETE (table name, condition)
        Yii::$app->db->createCommand()->delete('user', 'status = 0')->execute();