如何编写查询来使用CDbCriteria计算yii中的外键？

Question

I have tables Ads with column AdsId,ClientId and table Assigned . Assigned has AdsId as foreign key. I want to count the number of AdsId in Assigned for given ClientId. I have the following query which works but I am not sure if its the best way. How can I run the same query in yii? Hope I made my question clear.

SELECT A. * , (
SELECT COUNT( B.AdsId ) 
FROM Assigned AS B
WHERE B.AdsId = A.AdsId
AND A.ClientId =1
)
FROM Ads AS A
WHERE A.ClientId =1
LIMIT 0 , 30

Answer 1

First declare a relation in your model relations function

public function relations(){
     return array(
        ...
       'AdsIdCount'=> array(self::STAT,'Ads','AdsId'),
       //'VarName'=>array('RelationType', 'ClassName', 'ForeignKey', ...additional options)

     );
}

then in your in returned activeRecord results you can just call this count like this

$result = Assigned::model()->find($criteria); 

$result->adsIdCount ; // do logic here

or

$results = Assigned::model()->findAll($criteria); 
foreach ($results as $result){
    $result->adsIdCount ; // do logic here
}

see STAT relation for more details on how this works http://www.yiiframework.com/doc/guide/1.1/en/database.arr#statistical-query