本文介绍了MySQL where 子句和 avg() 作为子查询的排序的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
虽然我可以对别名子查询进行分组和排序，但我不能在 where 子句中使用别名.我需要改用联接吗?
Although I can group and order by on an aliased sub query, I can't use the alias in a where clause. Do I need to use a join instead?
作品:
SELECT entries.*,
(SELECT avg(value)
FROM `ratings`
WHERE ratings.entry_id = entries.id) as avg_rating
FROM `entries`
ORDER BY avg_rating DESC
失败(where 子句中的未知列 'avg_rating'"):
Fails ("unknown column 'avg_rating' in where clause"):
SELECT entries.*,
(SELECT avg(value)
FROM `ratings`
WHERE ratings.entry_id = entries.id) as avg_rating
FROM `entries`
WHERE avg_rating < '4.5000' ORDER BY avg_rating DESC
推荐答案
您可以使用 HAVING 子句而不是 WHERE 来做到这一点
You may be able to do this with a HAVING clause instead of a WHERE
语法
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