一个地区表 A
有字段
b 用户id
a 地区编号 如'420000'
表B
字段 b 编号 外键 A.b
c 状态 值 0 or 1
Hot int 点击次数 表C
字段 id 编号
c 编号 外键B.b
time 时间
e string 现在要查的内容是
1 按地区的用户数 降序排
2 查每个地区的一个用户的信息(这个用户是hot 最高的 ,time 最新的)
3 要查出A a和b 字段 C中e 和id 字段
4 B表中的c=1
这4个条件同时满足 一次查出来
昨天发的大家以为是1个 个查了
有字段
b 用户id
a 地区编号 如'420000'
表B
字段 b 编号 外键 A.b
c 状态 值 0 or 1
Hot int 点击次数 表C
字段 id 编号
c 编号 外键B.b
time 时间
e string 现在要查的内容是
1 按地区的用户数 降序排
2 查每个地区的一个用户的信息(这个用户是hot 最高的 ,time 最新的)
3 要查出A a和b 字段 C中e 和id 字段
4 B表中的c=1
这4个条件同时满足 一次查出来
昨天发的大家以为是1个 个查了
select A.a,A.b,B.*,C.e,C.[id] from B join A on A.地区编号=b.编号 join C on C.编号=B.编号 where not exists(select 1 from B Where 编号=B.编号 where B.Hot>Hot) and not exists(select 1 from C Where id=C.id where B.time>time) and c=1 order by A.地区编号 desc --在昨天的基础上修改一下,应该就可以了
A
uid area
1 42000
2 42000
3 42200B
uid hot state
1 52 1
2 82 1
3 36 1 C
id uid time c
1 1 2008-10-2 dd
2 1 2008-10-6 dd
3 2 2008-10-5 dd
4 2 2008-10-8 ss
5 3 2008-11-5 sss现在要查出来的结果是
uid area time c
2 42000 2008-10-6 dd
3 42200 2008-11-5 sss
from a,b
where a.id=b.id
1 按地区的用户数 降序排
2 查每个地区的一个用户的信息(这个用户是hot 最高的 ,time 最新的)
3 要查出A a和b 字段 C中e 和id 字段
4 B表中的c=1
这4个条件同时满足 一次查出来 A、B、C三表字段名与你的要求不符,检查一下
查出来了 用到not exists 结果虽然出来了
但是 不知道性能怎么样 当数据量很大的时候不知道怎么样
from Modl_view a
left join
(select count(Area) as [Count],Area from Modl_view
where Checked=1 group by Area)as c on a.Area=c.Area
left join (select * from ModelWorks where MWid in
(select max(MWid) from ModelWorks where Checked=1 group by Uid ))as d
on a.Uid=d.Uid
where a.Checked=1 and not exists
(select Hot from Modl_view b where b.Hot>a.Hot and a.Area=b.Area)
order by [Count] DESC 说明 把UserInfo 表和Modl 连成了一个视图了 Modl_view
create Modl_view
asSELECT dbo.Model.Uid, dbo.Model.Uname, dbo.Model.Age, dbo.Model.Hight, dbo.Model.Round, dbo.Model.HairType, dbo.Model.Mtype,
dbo.Model.PerEnounce, dbo.Model.UpdateTime, dbo.Model.Hot, dbo.Model.Commend, dbo.Model.Ctime, dbo.Model.EnounceComm, dbo.Model.Etime,
dbo.Model.Checked, dbo.Model.Chktime, dbo.UserInfo.PetName, dbo.UserInfo.Name, dbo.UserInfo.Area
FROM dbo.Model INNER JOIN
dbo.UserInfo ON dbo.Model.Uid = dbo.UserInfo.Uid
where Checked=1 group by Area)as c on a.Area=c.Area 这个主要是为了排序
/******************************************************************************************************************************************************
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)