关于自动连接数据库

关于自动连接数据库,为什么比自行new一个CDbConnection要慢很多?

//手动连接数据库

$conn = new CDbConnection(‘mysql:host=127.0.0.1;dbname=test’, ‘root’, ‘password’);

$conn->enableParamLogging = 1;

$conn->tablePrefix = ‘tbl_’;

//以Yii::app()这种方式获取conn就会很慢,不知道是什么原因?

//$conn = Yii::app()->db;

$command = $conn->createCommand('SELECT * FROM tbl_main');

$data = $command->queryRow();

$this->render(‘index’);