数据库中一个表tmp,有两个字段id和name, id是主键,自动编号.我用下面的语句删除没想到有错误,请高手指点以下!
delete from tmp A where A.id not in (select min(B.id) from tmp B group by B.name)
delete from tmp A where A.id not in (select min(B.id) from tmp B group by B.name)
--> --> (Roy)生成測試數據 if not object_id('Tempdb..#T') is null
drop table #T
Go
Create table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2))
Insert #T
select 1,N'A',N'A1' union all
select 2,N'A',N'A2' union all
select 3,N'A',N'A3' union all
select 4,N'B',N'B1' union all
select 5,N'B',N'B2'
Go --I、Name相同ID最小的记录(推荐用1,2,3),保留最小一条
方法1:
delete a from #T a where exists(select 1 from #T where Name=a.Name and ID <a.ID) 方法2:
delete a from #T a left join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID where b.Id is null 方法3:
delete a from #T a where ID not in (select min(ID) from #T where Name=a.Name) 方法4(注:ID为唯一时可用):
delete a from #T a where ID not in(select min(ID)from #T group by Name) 方法5:
delete a from #T a where (select count(1) from #T where Name=a.Name and ID <a.ID)>0 方法6:
delete a from #T a where ID <>(select top 1 ID from #T where Name=a.name order by ID) 方法7:
delete a from #T a where ID>any(select ID from #T where Name=a.Name)
select * from #T 生成结果:
/*
ID Name Memo
----------- ---- ----
1 A A1
4 B B1 (2 行受影响)
*/
SQL查询重复处理记录
where A.name = B.name
/code]
delete from tmp A where A.Name not in (select B.Name from tmp B group by B.name having sum(B.name) = 1) insert into Tmp select distinct * from #temp1
这样就可以了
WHERE (id NOT IN
(SELECT MIN(id)
FROM tmp
GROUP BY name))