SQL SERVER 去掉重复记录

heshao2005

　　今天应一个网友的要求说帮他写一个SQL 语句
　　条件是：如果出现DataID,TableName出现多次只取第一条记录
　　
　　if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Votes]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[Votes]
GO
　　CREATE TABLE [dbo].[Votes] (
[ID] [bigint] IDENTITY (1, 1) NOT NULL ,
[CompanyID] [bigint] NOT NULL ,
[TableName] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,
[DataID] [bigint] NULL ,
[VoteUser] [varchar] (100) COLLATE Chinese_PRC_CI_AS NULL ,
[VoteTime] [datetime] NULL ,
[VoteIP] [varchar] (100) COLLATE Chinese_PRC_CI_AS NULL ,
[VoteType] [varchar] (100) COLLATE Chinese_PRC_CI_AS NULL ,
[VoteInfo] [varchar] (1000) COLLATE Chinese_PRC_CI_AS NULL
) ON [PRIMARY]
GO
　　我的写法:
　　select a.* from Votes a inner join (select min(ID) as ID from Votes group by DataID,TableName having (count(*)>1)) b on a.ID =b.ID
union all
select a.* from Votes a inner join (select min(ID) as ID from Votes group by DataID,TableName having (count(*)=1)) b on a.ID =b.ID
　　
　　优化一下：
　　
　　select a.* from Votes a inner join (select min(ID) as ID from Votes group by DataID,TableName ) b on a.ID =b.ID