MySql按条件不同的顺序

Question

我有我的mysql查询

SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests` WHERE 1 ORDER BY `level` DESC, `pexpdate` DESC, `adddate` DESC

给我回报

问题是，如果部分有级别＆gt; 0很好，按pexpdate排序，第二部分，其中level = 0，必须按adddate排序，而不是pexpdate。

我试过了：

WHERE 1 ORDER BY ORDER BY `level` desc, `PExpDate` desc, `AddDate` desc
WHERE 1 ORDER BY IF(`level`, `PExpDate`, `AddDate`) DESC
WHERE 1 ORDER BY level DESC, ifnull(PExpDate, AddDate) DESC LIMIT 5

问题：如何通过adddate对level = 0的部分结果进行排序。

Answer 1

首先，WHERE 1部分是无用的。您不需要WHERE来指定ORDER子句。

然后，使用UNION。

SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests` WHERE `level` <> 0 ORDER BY `level` DESC, `pexpdate` DESC, `adddate` DESC
UNION
SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests` WHERE `level` = 0 ORDER BY `adddate` DESC

Answer 2

您可以使用UNION

SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests` WHERE `level`>0 ORDER BY `level` DESC, `pexpdate` DESC
UNION
SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests` WHERE `level`=0 ORDER BY `adddate`

Answer 3

尝试没有UNION

  SELECT `adddate`, `pexpdate`, `level` FROM `localhost-tests`
  ORDER BY CASE  WHEN `level`>0 THEN `level` , `pexpdate` , `adddate` 
                 WHEN `level`=0 THEN `adddate`
           END DESC

Answer 4

解决方案很简单，乘以2列并按结果排序

SELECT *, `level` * UNIX_TIMESTAMP(`pexpdate`) as `BonusDate` FROM `localhost-tests` WHERE 1 ORDER BY `BonusDate` DESC, `adddate` DESC