Symfony2 Doctrine Count子查询

How can i implement this in Doctrine?

SELECT 
(SELECT count(*) 
FROM article
JOIN comments ON article.id = comments.article_id  
WHERE
date(article.created) = '2015-02-06'
AND 
article.id = 1) as a, 

(SELECT count(*)
 FROM  article
 JOIN comments ON article.id = comments.article_id  
 WHERE
 date(article.created) = '2015-02-05'
 AND 
  article.id = 1) as b

FROM article
GROUP BY article.id
LIMIT 1

This is what i am trying so far

public function createMyQuery($cdate, $aid){
    $parameters = array(
            'cdate' => $cdate,
            'aid' => $aid,
        );

        $q = $this->getEntityManager()->createQueryBuilder()
                ->select(' ')
                ->addSelect('count(a.id)')
                ->from('ITJariSocialNetworkBundle:Article', 'a')
        ->where('article.created', ':cdate'))
        ->andWhere('article.id = :aid')
        setParameters->($parameters)
        ;

    return $q->getQuery();
}


//then i am looping on the calling of the function as following:

for($i=0; $i<7; $i++){
    $postDate = date('Y-m-d',strtotime("-" .$i."days"));
    $query = $this->createMyQuery(postDate, $aid);
}
$query->execute();

expecting to get the count of all the sub queries however i am getting Exception error result i thing the reason is i am doing the query in a wrong way