假设有表 A
ID,p(部门),t(时间),n(签到人)
1,销售部,2011-8-24 7:50,nn1
4,销售部,2011-8-24 7:55,nn2
2,质检部,2011-8-24 7:53,nn5
6,质检部,2011-8-24 7:56,nn4要求查询统计出每个部门第一个(最多一个)签到人,如:销售部,2011-8-24 7:50,nn1
质检部,2011-8-24 7:53,nn5请问,这个SQL应该怎么写,能否不用 join
ID,p(部门),t(时间),n(签到人)
1,销售部,2011-8-24 7:50,nn1
4,销售部,2011-8-24 7:55,nn2
2,质检部,2011-8-24 7:53,nn5
6,质检部,2011-8-24 7:56,nn4要求查询统计出每个部门第一个(最多一个)签到人,如:销售部,2011-8-24 7:50,nn1
质检部,2011-8-24 7:53,nn5请问,这个SQL应该怎么写,能否不用 join
select *,rid=row_number() over (partition by p order by t)
from A
where rid=1
(select row_number() over(partition by P order by t) no,* from tb) t
where no=1
replace(min(convert(char(19),t,120)+convert(varchar(32),n)),
min(convert(char(19),t,120)),'') as n
from A
group by P
select *
from tb t
where id = (select top 1 id from tb where P = t.P order by id)
假设有表 A
ID,p(部门),t(时间),n(签到人)
1,销售部,2011-8-24 7:50,nn1
4,销售部,2011-8-24 7:55,nn2
2,质检部,2011-8-24 7:53,nn5
6,质检部,2011-8-24 7:56,nn4要求查询统计出每个部门第一个(最多一个)签到人,如:销售部,2011-8-24 7:50,nn1
质检部,2011-8-24 7:53,nn5
;with
dd as(
select *,row_number()over(partition by p order by case(t as date))nb
from a
)
select p,t,n
from dd
where nb=1-------试试
--测试例子
if object_id('tb','u') is not null
drop table tb
gocreate table tb(
ID int,
p varchar(10),
t datetime,
n varchar(10)
)
goinsert into tb(ID,p,t,n)
select 1,'销售部','2011-8-24 7:50','nn1'
union all select 4,'销售部','2011-8-24 7:55','nn2'
union all select 2,'质检部','2011-8-24 7:53','nn5'
union all select 6,'质检部','2011-8-24 7:56','nn4'
go--select * from tbselect id,p,t from (
select *,rid=row_number() over (partition by p order by t)
from tb) t
where rid=1
godrop table tb
go/*
1 销售部 2011-08-24 07:50:00.000
2 质检部 2011-08-24 07:53:00.000
dd as(
select *,row_number()over(partition by p order by case(t as datetime))nb
from a
)
select p,t,n
from dd
where nb=1
(select row_number() over(partition by P order by t) no,* from tb) t
where no=1++ 1
2、ID是唯一的,但ID大的时间不一定大,也就说,ID和t的递增没有对应关系
select * from a
where id in (
select min(id) from a
group by p
)
where id in (
select min(id) from a
group by p,t
)
select * from a
right join (
select p,min(t) t from a
group by p
) b on a.p=b.p and a.t=b.t
(select (select count(1) from tb where t1.p=p and t1.t>t) rn,* from tb t1) t
where rn=1
select b.* from
(select p,min(t) t,n from A group by p,n) b,
(select p,min(t) t from A group by p) c
where b.p=c.p and b.t=c.t
select ID,p,t,n from (select (select count(1) from tb where t1.p=p and t1.t>t) rn,* from tb t1) t where rn=0
*
from
tb t
where
t=(select min(t) from tb where p=t.p)
/******************************************************************************************************************************************************
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)
*/
*
from
tb t
where
t=(select min(t) from tb where p=t.p)