MSSQL处理表重复记录

核心提示：5 B B2(2 行受影响)*/--3、删除重复记录没有大小关系时，处理重复值--> --> (Roy)生成測試數據if not object_id('Tempdb..#T') is nulldrop table #TGoCreate table #T([Num]

5 B B2

(2 行受影响)
*/

--3、删除重复记录没有大小关系时，处理重复值

--> --> (Roy)生成測試數據

if not object_id('Tempdb..#T') is null
drop table #T
Go
Create table #T([Num] int,[Name] nvarchar(1))
Insert #T
select 1,N'A' union all
select 1,N'A' union all
select 1,N'A' union all
select 2,N'B' union all
select 2,N'B'
Go

方法1:
if object_id('Tempdb..#') is not null
drop table #
Select distinct * into # from #T--排除重复记录结果集生成临时表#

truncate table #T--清空表

insert #T select * from # --把临时表#插入到表#T中

--查看结果
select * from #T

/*
Num Name
----------- ----
1 A
2 B

(2 行受影响)
*/

--重新执行测试数据后用方法2
方法2:

alter table #T add ID int identity--新增标识列
go
delete a from #T a where exists(select 1 from #T where Num=a.Num and Name=a.Name and ID>a.ID)--只保留一条记录
go
alter table #T drop column ID--删除标识列

--查看结果
select * from #T

/*
Num Name
----------- ----
1 A
2 B

(2 行受影响)

*/

--重新执行测试数据后用方法3
方法3:
declare Roy_Cursor cursor local for
select count(1)-1,Num,Name from #T group by Num,Name having count(1)>1
declare @con int,@Num int,@Name nvarchar(1)
open Roy_Cursor
fetch next from Roy_Cursor into @con,@Num,@Name
while @@Fetch_status=0
begin
set rowcount @con;
delete #T where Num=@Num and Name=@Name
set rowcount 0;
fetch next from Roy_Cursor into @con,@Num,@Name
end
close Roy_Cursor
deallocate Roy_Cursor

--查看结果
select * from #T
/*
Num Name
----------- ----
1 A
2 B

(2 行受影响)
*/