/*
字段1 字段2 字段3 字段4 字段5 字段6 字段7
33 xxxx1 xxxx xxxx xxxx xx xx
33 xxxx2 sss xzs d sd sd
33 xxxx3 sss xzs d sd sd
44 adas1 ee dsd esf dsq dswe
44 adas2 ee dsd esf dsq dswe
44 adas3 ee dsd esf dsq dswe
.
.
.
返回
字段1 字段2 字段3 字段4 字段5 字段6 字段7
33 xxxx1 xxxx xxxx xxxx xx xx
44 adas1 ee dsd esf dsq dswe
就是以字段为基准,返回其中的第一行信息
where 字段2=(select min(字段2) from tb where 字段1=t.字段1)
or
select * from tb t
where not exists(select 1 from tb where 字段1=t.字段1 and 字段2<t.字段2)
/******************************************************************************************************************************************************
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)
*/
--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)
*/--2、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)
*/--3、删除重复记录没有大小关系时,处理重复值
--> --> (Roy)生成測試數據
if not object_id('Tempdb..#T') is null
drop table #T
Go
Create table #T([Num] int,[Name] nvarchar(1))
Insert #T
select 1,N'A' union all
select 1,N'A' union all
select 1,N'A' union all
select 2,N'B' union all
select 2,N'B'
Go方法1:
if object_id('Tempdb..#') is not null
drop table #
Select distinct * into # from #T--排除重复记录结果集生成临时表#truncate table #T--清空表insert #T select * from # --把临时表#插入到表#T中--查看结果
select * from #T/*
Num Name
----------- ----
1 A
2 B(2 行受影响)
*/--重新执行测试数据后用方法2
方法2:alter table #T add ID int identity--新增标识列
go
delete a from #T a where exists(select 1 from #T where Num=a.Num and Name=a.Name and ID>a.ID)--只保留一条记录
go
alter table #T drop column ID--删除标识列--查看结果
select * from #T/*
Num Name
----------- ----
1 A
2 B(2 行受影响)*/--重新执行测试数据后用方法3
方法3:
declare Roy_Cursor cursor local for
select count(1)-1,Num,Name from #T group by Num,Name having count(1)>1
declare @con int,@Num int,@Name nvarchar(1)
open Roy_Cursor
fetch next from Roy_Cursor into @con,@Num,@Name
while @@Fetch_status=0
begin
set rowcount @con;
delete #T where Num=@Num and Name=@Name
set rowcount 0;
fetch next from Roy_Cursor into @con,@Num,@Name
end
close Roy_Cursor
deallocate Roy_Cursor--查看结果
select * from #T
/*
Num Name
----------- ----
1 A
2 B(2 行受影响)
*/
订单号相当于字段1 完成状态相当于字段2订单号 完成状态 客户名称 需求数量
888888 下单 火枪 1
666666 完成 黑炭 1
666666 完成 黑炭 1
666666 完成 黑炭 1
666666 完成 黑炭 1
666666 完成 黑炭 1//查询语句按照上面select * from tb_case
where not exists(select 1 from tb_case where 订单号=tb_case.订单号 and 完成状态<tb_case.完成状态)
from tb_case t
where
not exists(select 1 from tb_case where 订单号=t.订单号 and 完成状态<t.完成状态)
select distinct * from [tb]
where not exists (select 1 from table1 where 字段1=t.字段1 and 字段2<t.字段2)
where not exists (select 1 from table1 where 字段1=t.字段1 and 字段2 <t.字段2)顶...
create table tb(id int,c1 varchar(10),c2 varchar(10),c3 varchar(10),c4 varchar(10),c5 varchar(10),c6 varchar(10))insert into tb select
33,'xxxx1','xxxx','xxxx','xxxx','xx','xx' union all select
33,'xxxx2','sss','xzs','d','sd','sd' union all select
33,'xxxx3','sss','xzs','d','sd','sd' union all select
44,'adas1','ee','dsd','esf','dsq','dswe' union all select
44,'adas2','ee','dsd','esf','dsq','dswe' union all select
44,'adas3','ee','dsd','esf','dsq','dswe'
select v.*
from (select distinct id from tb) t
cross apply
(select top(1) * from tb where t.id=id) vid c1 c2 c3 c4 c5 c6
----------- ---------- ---------- ---------- ---------- ---------- ----------
33 xxxx1 xxxx xxxx xxxx xx xx
44 adas1 ee dsd esf dsq dswe(2 行受影响)
create table tb(id int,c1 varchar(10),c2 varchar(10),c3 varchar(10),c4 varchar(10),c5 varchar(10),c6 varchar(10))insert into tb select
33,'xxxx1','xxxx','xxxx','xxxx','xx','xx' union all select
33,'xxxx2','sss','xzs','d','sd','sd' union all select
33,'xxxx3','sss','xzs','d','sd','sd' union all select
44,'adas1','ee','dsd','esf','dsq','dswe' union all select
44,'adas2','ee','dsd','esf','dsq','dswe' union all select
44,'adas3','ee','dsd','esf','dsq','dswe'
select * from tb t
where not exists (select 1 from tb where id=t.id and c1 <t.c1)id c1 c2 c3 c4 c5 c6
----------- ---------- ---------- ---------- ---------- ---------- ----------
33 xxxx1 xxxx xxxx xxxx xx xx
44 adas1 ee dsd esf dsq dswe(2 行受影响)