Question

我有一张简单的表格：

CREATE  TABLE `dev_a4a`.`test` (   `id` INT UNSIGNED NOT NULL
AUTO_INCREMENT ,   `type` VARCHAR(45) NOT NULL ,   `priority` INT NOT
NULL ,   PRIMARY KEY (`id`) );

以下行：

id|type |priority
1 |long |8
2 |long |3
3 |short|9
4 |short|1

我希望按条件排序行：

SELECT (RAND() * priority) as prio, type, priority FROM test
ORDER BY (IF(type = 'short', '2', prio)) DESC, id DESC

结果我得到的行没有按条件排序。每次看起来都是随机的。这是可能的结果之一：

prio                 | type  | priority
'0.05013570194145264', 'long', '8'
'2.9015473750434326', 'long', '3'
'0.320064320527077', 'short', '1'
'7.598900996706356', 'short', '9'

我做错了什么？

预期结果：

prio                 | type  | priority
'2.9015473750434326', 'long', '3'  <- order by prio
'7.598900996706356', 'short', '9'  <- order by common value 2  
'0.320064320527077', 'short', '1'  <- order by common value 2
'0.05013570194145264', 'long', '8' <- order by prio

Answer 1

这个怎么样？

SELECT (RAND() * priority) as prio, type, priority ,CASE `type`
       WHEN 'short' THEN 2
       WHEN 'long' THEN 1

    END AS  t
FROM test
ORDER BY 3 DESC, id DESC

Answer 2

好的，我解决了这个问题：

SELECT CASE WHEN type = 'short' THEN 2 ELSE RAND() * priority END AS prio, type, priority FROM test ORDER BY prio DESC, id DESC

Mysql按if条件排序 - 错误的顺序

2 个答案: