doctrine createQueryBuilder count and not exists

    $qb = $this->o->createQueryBuilder('o');

        $sub = $this->em->createQueryBuilder();
        $sub->select("o.id");   //notice this : cause e.offer is foreign key of o.id
        $sub->from(ExcludedByOffer::class, "e");
        $sub->andWhere('e.offer = o.id') 
            ->andWhere('e.aff = :aff');


        $qb->select('count(o.id)')
            ->where('o.adv=:adv') 
            ->andWhere($qb->expr()->not($qb->expr()->exists($sub->getDQL())))
            ->setParameters(['adv'     => $adv,
                             'aff'      => $aff  
            ]);
        return $qb->getQuery()->getSingleScalarResult();

参考

https://stackoverflow.com/questions/31536137/doctrine-not-exists-subquery/31536545
https://stackoverflow.com/questions/9214471/count-rows-in-doctrine-querybuilder