字段唯一查询
mess
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id(递增/int) name(姓名/nvarchar) mess(留言内容/nvarchar)
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1 AA **
2 BB **
3 AA **
4 AA **
5 BB **
6 EE **
7 FF **
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我想查询出的结果是
1 AA **
2 BB **
6 CC **
7 DD **
解决方法：
-方法一
Select * From mess A Where Not Exists(Select id From mess Where name = A.name And id < A.id)
--方法二
Select * From mess A Where id In (Select Min(id) From mess Group By name)
--方法三
Select * From mess A Where id = (Select Min(id) From mess Where name = A.name)
--方法四
Select A.* From mess A Inner Join (Select name, Min(id) As id From mess Group By name) B On A.name = B.name And A.id = B.id