symfony - Doctrine2 - 需要一些帮助来修改工作 dql

Question

我有以下 dql SELECT 查询，该查询有效：

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

AVG(r.score)如果是 0 或 null ，我想做的是让它返回 0 。我只是不知道该怎么做。是否可以执行以下操作：

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

Answer 1

由于不能在WHERE子句中使用聚合函数，因此必须HAVING改用。这应该够了吧：

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

您是否正在寻找 mysql IFNULL的替代品来替代学说查询构建器。看看这个问题。

Answer 3

将我的 (INNER) JOIN 更改为 LEFT OUTER JOIN 给了我想要的结果。