guid datetime gasstation
1 2009-10-1 2
2 2009-10-1 3
3 2009-10-2 2
4 2009-10-2 2
5 2009-10-3 2
6 2009-10-3 4 要求删除同一天内,gasstation号码不同的数据,保留guid号较小的那条数据,删除后结果:guid datetime gasstation
1 2009-10-1 2
3 2009-10-2 2
4 2009-10-2 2
5 2009-10-3 2
1 2009-10-1 2
2 2009-10-1 3
3 2009-10-2 2
4 2009-10-2 2
5 2009-10-3 2
6 2009-10-3 4 要求删除同一天内,gasstation号码不同的数据,保留guid号较小的那条数据,删除后结果:guid datetime gasstation
1 2009-10-1 2
3 2009-10-2 2
4 2009-10-2 2
5 2009-10-3 2
go
--> -->
if not object_ID(N'Tempdb..#T') is null
drop table #T
Go
Create table #T([guid] int,[datetime] Datetime,[gasstation] int)
Insert #T
select 1,'2009-10-1',2 union all
select 2,'2009-10-1',3 union all
select 3,'2009-10-2',2 union all
select 4,'2009-10-2',2 union all
select 5,'2009-10-3',2 union all
select 6,'2009-10-3',4
Go
DELETE a from #T AS a
WHERE EXISTS(SELECT 1 FROM #T WHERE DATEDIFF(dd,[datetime],a.[datetime])=0 HAVING COUNT(DISTINCT [gasstation])>1 )
AND EXISTS(SELECT 1 FROM #T WHERE DATEDIFF(dd,[datetime],a.[datetime])=0 AND [guid]<a.[guid] )goSELECT * FROM #T
/*
guid datetime gasstation
1 2009-10-01 00:00:00.000 2
3 2009-10-02 00:00:00.000 2
4 2009-10-02 00:00:00.000 2
5 2009-10-03 00:00:00.000 2
*/
go
--> -->
if not object_ID(N'Tempdb..#T') is null
drop table #T
Go
Create table #T([guid] int,[datetime] Datetime,[gasstation] int)
Insert #T
select 1,'2009-10-1',2 union all
select 2,'2009-10-1',3 union all
select 3,'2009-10-2',2 union all
select 4,'2009-10-2',2 union all
select 5,'2009-10-3',2 union all
select 6,'2009-10-3',4
GoDELETE b
FROM (SELECT [datetime] FROM #T GROUP BY [datetime] HAVING COUNT(DISTINCT [gasstation])>1)a
INNER JOIN #T AS b ON a.[datetime]=b.[datetime]
WHERE EXISTS(SELECT 1 FROM #T WHERE [datetime]=b.[datetime] AND [guid]<b.[guid] )goSELECT * FROM #T
/*
guid datetime gasstation
1 2009-10-01 00:00:00.000 2
3 2009-10-02 00:00:00.000 2
4 2009-10-02 00:00:00.000 2
5 2009-10-03 00:00:00.000 2
*/
create table #t([guid] int,[datetime] datetime,gasstation int);
insert into #t select 1,'2009-10-1',2 union all
select 2,'2009-10-1',3 union all
select 3,'2009-10-2',2 union all
select 4,'2009-10-2',2 union all
select 5,'2009-10-3',2 union all
select 6,'2009-10-3',4 union all
select 7,'2009-10-3',3 union all
select 8,'2009-10-3',3;--select * from #t;
delete a from #t a where exists(select 1 from #t b where b.datetime=a.[datetime] and b.gasstation<a.gasstation);
select * from #t;drop table #t;/*
guid datetime gasstation
----------- ----------------------- -----------
1 2009-10-01 00:00:00.000 2
3 2009-10-02 00:00:00.000 2
4 2009-10-02 00:00:00.000 2
5 2009-10-03 00:00:00.000 2
*/
--> --> (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)
*/
--II、Name相同ID保留最大的一条记录: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 max(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 max(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 max(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 desc)方法7:
delete a from #T a where ID<any(select ID from #T where Name=a.Name)
select * from #T
/*
ID Name Memo
----------- ---- ----
3 A A3
5 B B2(2 行受影响)
*/
where not exists (select 1 from t1 where a.guid>guid and a.[datetime]=[datatime])