--保留b,c重复是,ID最小的. delete tb from tb t where id not in (select min(id) from tb where b = t.b and c = t.c) --保留b,c重复是,ID最大的. delete tb from tb t where id not in (select max(id) from tb where b = t.b and c = t.c)
或者一张表的字段有100个。如何做?谢谢。--保留ID最小的. delete tb from tb t where id not in (select min(id) from tb where c1 = t.c1 and c2 = t.c2 ... and c100 = t.c100) --保留ID最大的. delete tb from tb t where id not in (select max(id) from tb where c1 = t.c1 and c2 = t.c2 ... and c100 = t.c100)
--------------------------------------------- --> Author : jinjazzli --> Target : ---->1000 --> Date : 2009-12-11 16:23:25 --> Version: SQL Server 2005 ---------------------------------------------
--> 测试数据: @tb declare @tb table (id int,c1 varchar(1),c2 varchar(1)) insert into @tb select 1,'a','b' union all select 2,'a','b' union all select 3,'a','b'delete a from @tb a where exists(select 1 from @tb where c1=a.c1 and c2=a.c2 and id>a.id)select * from @tb id c1 c2 ----------- ---- ---- 3 a b(1 行受影响)
找出这样的数据可以用 group by + having count(b+c)>1
删除重复记录有大小关系时,保留大或小其中一个记录 --> --> (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) */
有个思路,把所有列合并成一列,然后比较合并后的列值.估计是要写存储过程的... 关注ing!!
--------------------------------------------- --> Author : jinjazzli --> Target : ---->1000 --> Date : 2009-12-11 16:23:25 --> Version: SQL Server 2005 ---------------------------------------------
--> 测试数据: @tb declare @tb table (id int,c1 varchar(1),c2 varchar(1)) insert into @tb select 1,'a','b' union all select 2,'a','b' union all select 3,'a','b'delete a from @tb a where exists(select 1 from @tb where c1=a.c1 and c2=a.c2 and id>a.id)select * from @tb id c1 c2 ----------- ---- ---- 3 a b(1 行受影响)本人觉得这个不错啊!! LZ可以考虑
--> 测试数据: @tb declare @tb table (id int,c1 varchar(1),c2 varchar(1)) insert into @tb select 1,'a','b' union all select 2,'a','b' union all select 3,'a','b' --グルプの中に最大Idを取得する。 select max(id), c1,c2 from @tb group by c1,c2 --グルプの中に最小Idを取得する select min(id), c1,c2 from @tb group by c1,c2 以上
delete tb from tb t where id not in (select min(id) from tb where b = t.b and c = t.c)
--保留b,c重复是,ID最大的.
delete tb from tb t where id not in (select max(id) from tb where b = t.b and c = t.c)
delete tb from tb t where id not in (select min(id) from tb where c1 = t.c1 and c2 = t.c2 ... and c100 = t.c100)
--保留ID最大的.
delete tb from tb t where id not in (select max(id) from tb where c1 = t.c1 and c2 = t.c2 ... and c100 = t.c100)
--> Author : jinjazzli
--> Target : ---->1000
--> Date : 2009-12-11 16:23:25
--> Version: SQL Server 2005
---------------------------------------------
--> 测试数据: @tb
declare @tb table (id int,c1 varchar(1),c2 varchar(1))
insert into @tb
select 1,'a','b' union all
select 2,'a','b' union all
select 3,'a','b'delete a
from @tb a
where exists(select 1 from @tb where c1=a.c1 and c2=a.c2 and id>a.id)select * from @tb
id c1 c2
----------- ---- ----
3 a b(1 行受影响)
--> --> (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)
*/
关注ing!!
--> Author : jinjazzli
--> Target : ---->1000
--> Date : 2009-12-11 16:23:25
--> Version: SQL Server 2005
---------------------------------------------
--> 测试数据: @tb
declare @tb table (id int,c1 varchar(1),c2 varchar(1))
insert into @tb
select 1,'a','b' union all
select 2,'a','b' union all
select 3,'a','b'delete a
from @tb a
where exists(select 1 from @tb where c1=a.c1 and c2=a.c2 and id>a.id)select * from @tb
id c1 c2
----------- ---- ----
3 a b(1 行受影响)本人觉得这个不错啊!!
LZ可以考虑
declare @tb table (id int,c1 varchar(1),c2 varchar(1))
insert into @tb
select 1,'a','b' union all
select 2,'a','b' union all
select 3,'a','b'
--グルプの中に最大Idを取得する。
select max(id), c1,c2 from @tb group by c1,c2
--グルプの中に最小Idを取得する
select min(id), c1,c2 from @tb group by c1,c2
以上