批次号(int) 员工编号(int) 姓名(varchar) 提示:salbatnum与emp_id 是联合主键 salbatnum emp_id name aa bb cc99000002720080601 990002968 孔杰 50.0 671.0 392.0
99000002720080703 990000407 周波 12.0 44.0 490.0
99000002720080601 990000407 周波 60.0 163.0 200.0
99000002720080605 990003174 王新佑 126.0 500.0 21.0
99000002720080501 990000405 张三 180.0 693.0 419.0
99000002720080601 990000405 张三 300.0 47.1 355.0保留最大批次号的人的记录,同时消除重复记录。查询结果99000002720080601 990002968 孔杰 50.0 671.0 392.0
99000002720080703 990000407 周波 12.0 44.0 490.0
99000002720080605 990003174 王新佑 126.0 500.0 21.0
99000002720080601 990000405 张三 300.0 47.0 355.0
(爱新觉罗.毓华 2007-10-23于浙江杭州)
/*
数据如下:
name val memo
a 2 a2(a的第二个值)
a 1 a1--a的第一个值
a 3 a3:a的第三个值
b 1 b1--b的第一个值
b 3 b3:b的第三个值
b 2 b2b2b2b2
b 4 b4b4
b 5 b5b5b5b5b5
*/
--创建表并插入数据:
create table tb(name varchar(10),val int,memo varchar(20))
insert into tb values('a', 2, 'a2(a的第二个值)')
insert into tb values('a', 1, 'a1--a的第一个值')
insert into tb values('a', 3, 'a3:a的第三个值')
insert into tb values('b', 1, 'b1--b的第一个值')
insert into tb values('b', 3, 'b3:b的第三个值')
insert into tb values('b', 2, 'b2b2b2b2')
insert into tb values('b', 4, 'b4b4')
insert into tb values('b', 5, 'b5b5b5b5b5')
go--一、按name分组取val最大的值所在行的数据。
--方法1:
select a.* from tb a where val = (select max(val) from tb where name = a.name) order by a.name
--方法2:
select a.* from tb a where not exists(select 1 from tb where name = a.name and val > a.val)
--方法3:
select a.* from tb a,(select name,max(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name
--方法4:
select a.* from tb a inner join (select name , max(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name
--方法5
select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name
/*
name val memo
---------- ----------- --------------------
a 3 a3:a的第三个值
b 5 b5b5b5b5b5
*/--二、按name分组取val最小的值所在行的数据。
--方法1:
select a.* from tb a where val = (select min(val) from tb where name = a.name) order by a.name
--方法2:
select a.* from tb a where not exists(select 1 from tb where name = a.name and val < a.val)
--方法3:
select a.* from tb a,(select name,min(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name
--方法4:
select a.* from tb a inner join (select name , min(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name
--方法5
select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val < a.val) order by a.name
/*
name val memo
---------- ----------- --------------------
a 1 a1--a的第一个值
b 1 b1--b的第一个值
*/--三、按name分组取第一次出现的行所在的数据。
select a.* from tb a where val = (select top 1 val from tb where name = a.name) order by a.name
/*
name val memo
---------- ----------- --------------------
a 2 a2(a的第二个值)
b 1 b1--b的第一个值
*/--四、按name分组随机取一条数据。
select a.* from tb a where val = (select top 1 val from tb where name = a.name order by newid()) order by a.name
/*
name val memo
---------- ----------- --------------------
a 1 a1--a的第一个值
b 5 b5b5b5b5b5
*/--五、按name分组取最小的两个(N个)val
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val < a.val ) order by a.name,a.val
select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val) order by a.name,a.val
select a.* from tb a where exists (select count(*) from tb where name = a.name and val < a.val having Count(*) < 2) order by a.name
/*
name val memo
---------- ----------- --------------------
a 1 a1--a的第一个值
a 2 a2(a的第二个值)
b 1 b1--b的第一个值
b 2 b2b2b2b2
*/--六、按name分组取最大的两个(N个)val
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name,a.val
select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val desc) order by a.name,a.val
select a.* from tb a where exists (select count(*) from tb where name = a.name and val > a.val having Count(*) < 2) order by a.name
/*
name val memo
---------- ----------- --------------------
a 2 a2(a的第二个值)
a 3 a3:a的第三个值
b 4 b4b4
b 5 b5b5b5b5b5
*/
--七,如果整行数据有重复,所有的列都相同。
/*
数据如下:
name val memo
a 2 a2(a的第二个值)
a 1 a1--a的第一个值
a 1 a1--a的第一个值
a 3 a3:a的第三个值
a 3 a3:a的第三个值
b 1 b1--b的第一个值
b 3 b3:b的第三个值
b 2 b2b2b2b2
b 4 b4b4
b 5 b5b5b5b5b5
*/
--在sql server 2000中只能用一个临时表来解决,生成一个自增列,先对val取最大或最小,然后再通过自增列来取数据。
--创建表并插入数据:
create table tb(name varchar(10),val int,memo varchar(20))
insert into tb values('a', 2, 'a2(a的第二个值)')
insert into tb values('a', 1, 'a1--a的第一个值')
insert into tb values('a', 1, 'a1--a的第一个值')
insert into tb values('a', 3, 'a3:a的第三个值')
insert into tb values('a', 3, 'a3:a的第三个值')
insert into tb values('b', 1, 'b1--b的第一个值')
insert into tb values('b', 3, 'b3:b的第三个值')
insert into tb values('b', 2, 'b2b2b2b2')
insert into tb values('b', 4, 'b4b4')
insert into tb values('b', 5, 'b5b5b5b5b5')
goselect * , px = identity(int,1,1) into tmp from tbselect m.name,m.val,m.memo from
(
select t.* from tmp t where val = (select min(val) from tmp where name = t.name)
) m where px = (select min(px) from
(
select t.* from tmp t where val = (select min(val) from tmp where name = t.name)
) n where n.name = m.name)drop table tb,tmp/*
name val memo
---------- ----------- --------------------
a 1 a1--a的第一个值
b 1 b1--b的第一个值(2 行受影响)
*/
--在sql server 2005中可以使用row_number函数,不需要使用临时表。
--创建表并插入数据:
create table tb(name varchar(10),val int,memo varchar(20))
insert into tb values('a', 2, 'a2(a的第二个值)')
insert into tb values('a', 1, 'a1--a的第一个值')
insert into tb values('a', 1, 'a1--a的第一个值')
insert into tb values('a', 3, 'a3:a的第三个值')
insert into tb values('a', 3, 'a3:a的第三个值')
insert into tb values('b', 1, 'b1--b的第一个值')
insert into tb values('b', 3, 'b3:b的第三个值')
insert into tb values('b', 2, 'b2b2b2b2')
insert into tb values('b', 4, 'b4b4')
insert into tb values('b', 5, 'b5b5b5b5b5')
goselect m.name,m.val,m.memo from
(
select * , px = row_number() over(order by name , val) from tb
) m where px = (select min(px) from
(
select * , px = row_number() over(order by name , val) from tb
) n where n.name = m.name)drop table tb/*
name val memo
---------- ----------- --------------------
a 1 a1--a的第一个值
b 1 b1--b的第一个值(2 行受影响)
*/
where not exists(select 1 from tbname where emp_id = T.emp_id and salbatnum< T.salbatnum)
if object_id('tempdb.dbo.#T') is not null drop table #T
create table #T (salbatnum bigint,emp_id int,name nvarchar(6),aa numeric(4,1),bb numeric(4,1),cc numeric(4,1))
insert into #T
select 99000002720080601,990002968,'孔杰',50.0,671.0,392.0 union all
select 99000002720080703,990000407,'周波',12.0,44.0,490.0 union all
select 99000002720080601,990000407,'周波',60.0,163.0,200.0 union all
select 99000002720080605,990003174,'王新佑',126.0,500.0,21.0 union all
select 99000002720080501,990000405,'张三',180.0,693.0,419.0 union all
select 99000002720080601,990000405,'张三',300.0,47.1,355.0select *
from #T as t
where salbatnum=(select max(salbatnum) from #T where
emp_id=t.emp_id and name=t.name)
order by salbatnum/*
salbatnum emp_id name aa bb cc
-------------------- ----------- ------ --------------------------------------- --------------------------------------- ---------------------------------------
99000002720080601 990002968 孔杰 50.0 671.0 392.0
99000002720080601 990000405 张三 300.0 47.1 355.0
99000002720080605 990003174 王新佑 126.0 500.0 21.0
99000002720080703 990000407 周波 12.0 44.0 490.0(4 行受影响)
*/
insert into tb values('99000002720080601','990002968','孔杰',50.0,671.0,392.0)
insert into tb values('99000002720080703','990000407','周波',12.0,44.0,490.0)
insert into tb values('99000002720080601','990000407','周波',60.0,163.0,200.0)
insert into tb values('99000002720080605','990003174','王新佑',126.0,500.0,21.0)
insert into tb values('99000002720080501','990000405','张三',180.0,693.0,419.0)
insert into tb values('99000002720080601','990000405','张三',300.0,47.1,355.0)select tb.* from tb
inner join
(select emp_id,max(salbatnum) as salbatnum from tb
group by emp_id) aa
on tb.salbatnum=aa.salbatnum
and tb.emp_id=aa.emp_iddrop table tb
/*
salbatnum emp_id name aa bb cc
-------------------------------------------------------------------------
99000002720080605 990003174 王新佑 126.0 500.0 21.0
99000002720080601 990002968 孔杰 50.0 671.0 392.0
99000002720080703 990000407 周波 12.0 44.0 490.0
99000002720080601 990000405 张三 300.0 47.1 355.0(4行受影响)
*/
on tablename.emp_id= t.emp_id ,tablename.salbatnum = t.salbatnum
/******************************************************************************************************************************************************
Name相同ID最小或最大的记录整理人:中国风(Roy)日期:2008.06.06
******************************************************************************************************************************************************/--> --> (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
--1、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:
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
生成结果:
/*
ID Name Memo
----------- ---- ----
1 A A1
4 B B1(2 行受影响)
*/
--2、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:
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生成结果2:
/*
ID Name Memo
----------- ---- ----
3 A A3
5 B B2(2 行受影响)
*/
--> 测试数据: #T
if object_id('tempdb.dbo.#T') is not null drop table #T
create table #T (salbatnum bigint,emp_id int,name nvarchar(6),aa numeric(4,1),bb numeric(4,1),cc numeric(4,1))
insert into #T
select 99000002720080601,990002968,'孔杰',50.0,671.0,392.0 union all
select 99000002720080703,990000407,'周波',12.0,44.0,490.0 union all
select 99000002720080601,990000407,'周波',60.0,163.0,200.0 union all
select 99000002720080605,990003174,'王新佑',126.0,500.0,21.0 union all
select 99000002720080501,990000405,'张三',180.0,693.0,419.0 union all
select 99000002720080601,990000405,'张三',300.0,47.1,355.0select *
from #T as t
where not exists (select 1 from #t b where emp_id=t.emp_id and salbatnum>t.salbatnum)99000002720080601 990002968 孔杰 50.0 671.0 392.0
99000002720080703 990000407 周波 12.0 44.0 490.0
99000002720080605 990003174 王新佑 126.0 500.0 21.0
99000002720080601 990000405 张三 300.0 47.1 355.0