yii2执行原生sql语句

//子模块里设置了新数据库的连接

$connection =Yii::$app->controller->module->get('db'); 

//$connection =Yii::$app->db; //连接

$command = $connection->createCommand('SELECT * FROM sns_article_index_tbl WHERE art_id=37787');

$post = $command->queryOne();