Question

我有以下dql SELECT查询，它可以工作：

SELECT q AS question, AVG(r.score) AS average
  FROM MyBundle:Question q
  JOIN q.ratings r
  WHERE q.deleted IS NULL
  GROUP BY q.id
  ORDER BY q.id ASC

我想做的是，如果AVG(r.score)为0或null，则返回0。我只是不确定该怎么做。是否可以做类似的事情：

SELECT q AS question, (AVG(r.score) OR 0) AS average FROM....

Answer 1

由于您无法在WHERE子句中使用聚合函数，因此必须使用HAVING。这应该是诀窍：

SELECT q AS question, AVG(r.score) AS average
  FROM MyBundle:Question q
  JOIN q.ratings r
  WHERE q.deleted IS NULL
  GROUP BY q.id
  HAVING average IN (0, NULL)
  ORDER BY q.id ASC

Answer 2

您是否正在为doctrine查询构建器寻找mysql IFNULL的替代方案。看看这个question。

Answer 3

将我的（INNER）JOIN改为LEFT OUTER JOIN给了我正在寻找的结果。

Doctrine2 - 需要一些帮助来修改工作dql

3 个答案: