一个表,取得不同分类的各N条数据
如:现在有一张表:
title
category
两个字段.
现在有数据:
title category
1111 6
2222 7
3333 6
4444 6
现在想用一个sql取得,当N等于2时.
得到数据:1111 2222 333
------解决方案----------------------如果category相同的時候,title不會重復
--方法一:
Select * From 表 A
Where (Select Count(*) From 表 Where category = A.category And title < A.title) < 2
Order By category, title
--方法二:
Select * From 表 A
Where Exists (Select Count(*) From 表 Where category = A.category And title < A.title Having Count(*) < 2)
Order By category, title
--方法三:
Select * From 表 A
Where title In (Select TOP 2 title From 表 Where category = A.category Order By title)
Order By category, title