帮助需要sql查询，选择每个类别的最新5个列表

Question

我正在使用MySQL，我有一个带有项目的数据库表和5个类别（也有一个ID字段，autoincr，PK）我必须选择每个类别的最新5项，当我使用group by它返回最新的一项每个类别，我如何在一个查询中获得每个类别的前5项？

谢谢

Answer 1

你正好讨厌这个......

(select * from items where category_id=1 order by add_date desc limit 5)
union
(select * from items where category_id=2 order by add_date desc limit 5)
union
(select * from items where category_id=3 order by add_date desc limit 5)
union
(select * from items where category_id=4 order by add_date desc limit 5)
union
(select * from items where category_id=5 order by add_date desc limit 5);