gistfile1.txt

$qb->select("u")
            ->from("YourUserBundle:User", "u")
            ->join("u.Group", "g")
            ->join("g.Role", "r")
            ->where("r.role = :role");
        $query = $qb->getQuery();
        $query->setParameter("role", $role);

        $results = $query->getResult();