Question

我有一个sql表，Employee有4列。

编号
名称
地址
状态 - 固定类型（枚举）。拥有3个固定值 - OPEN，CLOSED和PENDING。

我们假设表中的总记录为200。

现在，我想形成一个返回的查询 -

50条状态为“OPEN”的随机记录。
25条状态为“已关闭”的随机记录。
45条随机记录，状态为“PENDING”。

我尝试过一个支离破碎的查询，它运行正常，但为整个场景寻找单一查询解决方案。

Select * from Employee a where a.Status = 'OPEN' ORDER BY RAND() LIMIT 50
Select * from Employee a where a.Status = 'CLOSED' ORDER BY RAND() LIMIT 25
Select * from Employee a where a.Status = 'PENDING' ORDER BY RAND() LIMIT 45

任何帮助都将受到高度赞赏。

Answer 1

您是需要将其作为单个查询（轻度痛苦）还是3个单独的查询？

作为3个单独的查询，最简单的选项就像

Select * from Employee where Status = 'OPEN' ORDER BY RAND() LIMIT 50;
Select * from Employee where Status = 'CLOSED' ORDER BY RAND() LIMIT 25;
Select * from Employee where Status = 'PENDING' ORDER BY RAND() LIMIT 45;

Answer 2

使用Union组合多个查询，并记住为每个子/父查询分配别名。

select * from ((Select * from Employee a where a.Status = 'OPEN' ORDER BY RAND() LIMIT 50) 
union 
(Select * from Employee b where b.Status = 'CLOSED' ORDER BY RAND() LIMIT 25) 
union 
(Select * from Employee c where c.Status = 'PENDING' ORDER BY RAND() LIMIT 45)) d;

我希望这对某人有用。

在MySql中获取随机记录

2 个答案: