Query caching yii framework

Question

I want to find the total score of the loggedin user & want to cache it. My code is:

$dependency = new CDbCacheDependency('SELECT MAX(id) FROM tbl_points_log where user_id='.Yii::app()->user->id);    
$sql='SELECT SUM( point) as user_point FROM tbl_points_log left join tbl_action on tbl_action.id = tbl_points_log.action_type_id where user_id='.Yii::app()->user->id;
$user_point = Yii::app()->db->cache(1000, $dependency)->createCommand($sql)->queryAll();

Is the above code correct? Do I have to make some changes in the config file to make query caching working? I just added

'cache' => array(
     'class' => 'CDbCache'
 ),

under components

var_dump($dependency->getHasChanged()); always evaluates to true, even if i did no changes into database, so why is that?

P.S Dont bother about the SQL statement. Its working!

Answer 1

the best way to find out that query results come from cache or database is that to turn on logging as follow and see the results

        'log'=>array(
            'class'=>'CLogRouter',
            'routes'=>array(
                array(
                    'class'=>'CFileLogRoute',
                    'levels'=>'error, warning',
                ), 
                array(
                    'class'=>'CWebLogRoute',
                ), 

            ),
        ),