--1、 select * from tb t where not exists (select 1 from tb where 序号 = t.序号 and id < t.id)--2、 select * from tb where id in (select min(id) from tb group by 序号)--3、 select * from tb t where id = (select min(id) from tb where 序号 = t.序号)
2005写法:with t as ( select *,row_number() over (partition by 序号 order by id desc) as Ranking from tb ) select * from t where Ranking=1
select * from tb t where id=(select min(id) from tb where 序号=t.序号)
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) */
如果返回的不仅仅只是id列,我觉的这样也是可以的: "SELECT MIN(id)AS id,mealName FROM [master].[dbo].[tb1] group by mealName"
--1、
select *
from tb t
where not exists (select 1 from tb where 序号 = t.序号 and id < t.id)--2、
select *
from tb
where id in (select min(id) from tb group by 序号)--3、
select *
from tb t
where id = (select min(id) from tb where 序号 = t.序号)
(
select *,row_number() over (partition by 序号 order by id desc) as Ranking
from tb
)
select *
from t
where Ranking=1
/******************************************************************************************************************************************************
1、Num、Name相同的重复值记录,没有大小关系只保留一条
2、Name相同,ID有大小关系时,保留大或小其中一个记录
整理人:中国风(Roy)日期:2008.06.06
******************************************************************************************************************************************************/--1、用于查询重复处理记录(如果列没有大小关系时2000用生成自增列和临时表处理,SQL2005用row_number函数处理)--> --> (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),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)
*/
"SELECT MIN(id)AS id,mealName FROM [master].[dbo].[tb1] group by mealName"