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if object_id("t0807") is not null
drop table t0807
go
create table t0807(AutoID int identity(1,1) primary key,[id] int,username varchar(10))
go
insert into t0807
select 1,"1" union all
select 4,"1" union all
select 4,"2" union all
select 6,"2" union all
select 2,"3" union all
select 7,"3"
go
--主键AutoID
delete  from  t0807
where AutoID not in
(
--查找出最小值
select AutoID from t0807 a
where [id]<=
(select min([id]) from t0807 b where a.username=b.username)
)
go
select * from t0807
(所影响的行数为 6 行)
(所影响的行数为 3 行)
AutoID      id          username   
----------- ----------- ----------
1           1           1
3           4           2
5           2           3
(所影响的行数为 3 行)

本文来源:http://www.gdgbn.com/shujuku/15598/