ORDER BY之后的GROUP BY [英] GROUP BY after ORDER BY

问题描述

我需要在 ORDER BY 之后执行 GROUP BY 。我不明白为什么MySQL不支持。
这是我的代码：

  SELECT 
`pages`.```，
 `content`.`id_language`，
 [...] 
 
 [...] 
 
 ORDER BY 
 FIND_IN_SET（`languages`。 '''''''）DESC 
 
 [GROUP BY] 
  

结果将如下所示：

  id | id_language | ... 
 1 3 
 1 1 
 2 3 
 2 5 
 2 1 
  

我需要按ID进行分组，我只需要第一个结果，并且需要保存在视图中。我无法使用SUBQUERY。

结果需要：

  id | id_language | ... 
 1 3 
 2 3 
  

注意：不要困惑于 id_language = 3 ，因为它不是一个规则。

解决方案

< pre $ SELECT id，idl
FROM（SELECT
`pages`.`id` as id，
`contents`.` id_language` as idl，
[...]

[...]

ORDER BY
FIND_IN_SET（`languages`.``id`，'3'） DESC
）d
GROUP BY d.id


I need to do GROUP BY after ORDER BY. I don't understand why MySQL doesn't support that. This is my code:

SELECT
    `pages`.`id`,
    `contents`.`id_language`,
    [...]

[...]

ORDER BY
    FIND_IN_SET(`languages`.`id`, '3') DESC

[the GROUP BY]

The results will be something like this:

id | id_language | ...
1    3
1    1
2    3
2    5
2    1

I need to group by ID, I need only the first result and I need to save in a view. I can't use a SUBQUERY because of that.

The result need to be:

id | id_language | ...
1    3
2    3

Note: Don't get confused by id_language = 3, because it isn't a rule.

解决方案

SELECT id, idl
FROM (SELECT
    `pages`.`id` as id,
    `contents`.`id_language` as idl,
    [...]

[...]

ORDER BY
    FIND_IN_SET(`languages`.`id`, '3') DESC
     ) d
GROUP BY d.id

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