有以下数据：
/*
ChID aa bb cc dd ee
22 A1 0.2 0 10.000 8.000
22 A1 0.3 0 10.000 4.000
22 A1 0.5 0.1 5.000 4.000
22 A1 0.6 0.1 15.000 2.000
33 A2 0.2 0 11.000 8.000
34 A3 0.3 0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000
35 A4 0.8 0 15.000 14.000
..
..
..
*/
要得出这样的结果,即按aa列分组，取出bb为最小值的记录:
/*
ChID aa bb cc dd ee
22 A1 0.2 0 10.000 8.000
33 A2 0.2 0 11.000 8.000
34 A3 0.3 0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000
*/
用一条sql语句怎么写？
/*
ChID aa bb cc dd ee
22 A1 0.2 0 10.000 8.000
22 A1 0.3 0 10.000 4.000
22 A1 0.5 0.1 5.000 4.000
22 A1 0.6 0.1 15.000 2.000
33 A2 0.2 0 11.000 8.000
34 A3 0.3 0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000
35 A4 0.8 0 15.000 14.000
..
..
..
*/
要得出这样的结果,即按aa列分组，取出bb为最小值的记录:
/*
ChID aa bb cc dd ee
22 A1 0.2 0 10.000 8.000
33 A2 0.2 0 11.000 8.000
34 A3 0.3 0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000
*/
用一条sql语句怎么写？
--> 测试数据：@T
declare @T table([ChID] int,[aa] varchar(2),[bb] numeric(2,1),[cc] numeric(2,1),[dd] numeric(5,3),[ee] numeric(5,3))
insert @T
select 22,'A1',0.2,0,10.000,8.000 union all
select 22,'A1',0.3,0,10.000,4.000 union all
select 22,'A1',0.5,0.1,5.000,4.000 union all
select 22,'A1',0.6,0.1,15.000,2.000 union all
select 33,'A2',0.2,0,11.000,8.000 union all
select 34,'A3',0.3,0,9.000,8.000 union all
select 35,'A4',0.5,0.1,12.000,10.000 union all
select 35,'A4',0.8,0,15.000,14.000select * from @T t
where [bb]=(select min([bb]) from @T where [aa]=t.[aa])/*
ChID aa bb cc dd ee
----------- ---- --------------------------------------- --------------------------------------- --------------------------------------- ---------------------------------------
22 A1 0.2 0.0 10.000 8.000
33 A2 0.2 0.0 11.000 8.000
34 A3 0.3 0.0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000
*/
你也可以使用其他方式。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),方法3在SQl05时，效率高于1、2
方法1:
Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID<a.ID)
方法2:
select a.* from #T a join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID
方法3:
select * from #T a where ID=(select min(ID) from #T where Name=a.Name)
方法4:
select a.* from #T a join #T b on a.Name=b.Name and a.ID>=b.ID group by a.ID,a.Name,a.Memo having count(1)=1
方法5:
select * from #T a group by ID,Name,Memo having ID=(select min(ID)from #T where Name=a.Name)
方法6:
select * from #T a where (select count(1) from #T where Name=a.Name and ID<a.ID)=0
方法7:
select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID)
方法8:
select * from #T a where ID!>all(select ID from #T where Name=a.Name)
方法9(注:ID为唯一时可用):
select * from #T a where ID in(select min(ID) from #T group by Name)
--SQL2005:
方法10:
select ID,Name,Memo from (select *,min(ID)over(partition by Name) as MinID from #T a)T where ID=MinID
方法11:
select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID) as MinID from #T a)T where MinID=1
生成结果:
/*
ID Name Memo
----------- ---- ----
1 A A1
4 B B1
(2 行受影响)
*/
--II、Name相同ID最大的记录,与min相反:
方法1:
Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID>a.ID)
方法2:
select a.* from #T a join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID order by ID
方法3:
select * from #T a where ID=(select max(ID) from #T where Name=a.Name) order by ID
方法4:
select a.* from #T a join #T b on a.Name=b.Name and a.ID<=b.ID group by a.ID,a.Name,a.Memo having count(1)=1
方法5:
select * from #T a group by ID,Name,Memo having ID=(select max(ID)from #T where Name=a.Name)
方法6:
select * from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)=0
方法7:
select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID desc)
方法8:
select * from #T a where ID!<all(select ID from #T where Name=a.Name)
方法9(注:ID为唯一时可用):
select * from #T a where ID in(select max(ID) from #T group by Name)
--SQL2005:
方法10:
select ID,Name,Memo from (select *,max(ID)over(partition by Name) as MinID from #T a)T where ID=MinID
方法11:
select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID desc) as MinID from #T a)T where MinID=1
生成结果2:
/*
ID Name Memo
----------- ---- ----
3 A A3
5 B B2
(2 行受影响)
*/
select 22,'A1',0.2,0,10.000,8.000 union all
select 22,'A1',0.3,0,10.000,4.000 union all
select 22,'A1',0.5,0.1,5.000,4.000 union all
select 22,'A1',0.6,0.1,15.000,2.000 union all
select 33,'A2',0.2,0,11.000,8.000 union all
select 34,'A3',0.3,0,9.000,8.000 union all
select 35,'A4',0.5,0.1,12.000,10.000 union all
select 35,'A4',0.8,0,15.000,14.000
---------------------------------------------------------------------------------------------------------------------
select distinct CHID,aa,
(select bb from (select ROW_NUMBER()over(partition by chid order by chid)id,bb,ChID from T) b where a.ChID=b.ChID and id=1 )as bb,
(select cc from (select ROW_NUMBER()over(partition by chid order by chid)id,cc,ChID from T) b where a.ChID=b.ChID and id=1 )as cc,
(select dd from (select ROW_NUMBER()over(partition by chid order by chid)id,dd,ChID from T) b where a.ChID=b.ChID and id=1 )as dd,
(select ee from (select ROW_NUMBER()over(partition by chid order by chid)id,ee,ChID from T) b where a.ChID=b.ChID and id=1 )as ee
from T a
-----------------------------------------------------------------------------------------------------
CHID aa bb cc dd ee
----------- ---- --------------------------------------- --------------------------------------- --------------------------------------- ---------------------------------------
22 A1 0.2 0.0 10.000 8.000
33 A2 0.2 0.0 11.000 8.000
34 A3 0.3 0.0 9.000 8.000
35 A4 0.5 0.1 12.000 10.000(4 行受影响)
select * from chi a where bb<=all(select min(bb) from chi where chid=a.chid and a.aa=aa)