doctrine2从中选择

Question

如何在Doctrine 2 QueryBuilder中执行此查询：

SELECT AVG（x.distance）avg_distance FROM（SELECT r。* FROM result r WHERE r.place_id =？GROUP BY r.place_id ORDER BY r.id DESC LIMIT 100

我尝试这样：

$dql = $qb
        ->select('r.*')
        ->from('CoreBundle:Result', 'r')
        ->where('r.place = :place')
        ->orderBy('r.id', 'DESC')
        ->setMaxResults(100)
        ->setParameter('place', $place)
        ->getDQL()
;

$result = $qb
            ->select('AVG(x.distance) avg_distance')
            ->from($dql, 'x')
            ->getQuery()
            ->getArrayResult();

但不起作用

SELECT r.* FROM': Error: Class 'SELECT' is not defined.

Answer 1

$sql = "SELECT AVG(x.distance) avg_distance FROM (SELECT r.* FROM result r WHERE r.place_id = :place_id ORDER BY r.id DESC LIMIT 100) x ";

$stmt = $this->em->getConnection()->prepare($sql);
$stmt->bindValue(':place_id', $place->getId());
$stmt->execute();
return $stmt->fetch();