sql语句问题

[crazyweed0907]

例如:
type detail
001 a
001 sss
001 gssfa
002 fdsf
002 fs
002 gahas
003 sdga
003 hahasg
003 gdsag
用一条sql语句得出每种(001 002 003) 的前两条记录

[-狙击手-]

select a.type,a.detail
from Ta a 
join Ta b
on a.type= b.type
group by a.type,a.detail
having count(case when a.detail <= b.detail then 1 else null end) < = 2 --可动态修改
order by a.type desc

[wzy_love_sly]

--转龟
--按某一字段分组取最大(小)值所在行的数据(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
*/

[pt1314917]

select id=identity(int,1,1),* into #temp from 表名

select * from #temp a where type in  ('001','002','003')
id in(select top 2 id from #temp where type=a.type order by id)

[-狙击手-]

declare @t table(type varchar(4),detail varchar(10))
insert @t select
'001','a' union select 
'001','sss' union select 
'001','gssfa' union select 
'002','fdsf' union select 
'002','fs' union select 
'002','gahas' union select 
'003','sdga' union select 
'003','hahasg' union select 
'003','gdsag'



select a.type,a.detail
from @t a 
join @t b
on a.type= b.type
group by a.type,a.detail
having count(case when a.detail <= b.detail then 1 else null end) < = 2 --可动态修改
order by a.type asc 

/*


type detail     
---- ---------- 
001  gssfa
001  sss
002  fs
002  gahas
003  hahasg
003  sdga

（所影响的行数为 6 行）
*/

[-狙击手-]

declare @t table(type varchar(4),detail varchar(10))
insert @t select
'001','a' union select 
'001','sss' union select 
'001','gssfa' union select 
'002','fdsf' union select 
'002','fs' union select 
'002','gahas' union select 
'003','sdga' union select 
'003','hahasg' union select 
'003','gdsag'



select a.type,a.detail
from @t a 
join @t b
on a.type= b.type
group by a.type,a.detail
having count(case when a.detail <= b.detail then 1 else null end) < = 2 --可动态修改
order by a.type asc 

/*


type detail     
---- ---------- 
001  gssfa
001  sss
002  fs
002  gahas
003  hahasg
003  sdga

（所影响的行数为 6 行）
*/

select a.* from @t a 
where exists (select count(*) 
              from @t
              where type = a.type and detail > a.detail having Count(*) < 2) 
order by a.type



/*


type detail     
---- ---------- 
001  gssfa
001  sss
002  fs
002  gahas
003  hahasg
003  sdga

（所影响的行数为 6 行）
*/
select a.* from @t a 
where exists (select count(*) 
              from @t
              where type = a.type and detail < a.detail having Count(*) < 2) 
order by a.type
/*
type detail     
---- ---------- 
001  a
001  gssfa
002  fdsf
002  fs
003  gdsag
003  hahasg

（所影响的行数为 6 行）
*/

select a.* 
from @t a 
where detail in (select top 2 detail 
              from @t where type=a.type 
              order by detail desc) 
order by a.type,a.detail
/*
type detail     
---- ---------- 
001  gssfa
001  sss
002  fs
002  gahas
003  hahasg
003  sdga

（所影响的行数为 6 行）
*/
select a.* 
from @t a 
where detail in (select top 2 detail 
              from @t where type=a.type 
              order by detail asc) 
order by a.type,a.detail
/*

type detail     
---- ---------- 
001  a
001  gssfa
002  fdsf
002  fs
003  gdsag
003  hahasg

（所影响的行数为 6 行）
*/

[pt1314917]

不好意思。上面的语句贴错了一个'and'

select id=identity(int,1,1),* into #temp from 表名

select * from #temp a where type in  ('001','002','003') and
id in(select top 2 id from #temp where type=a.type order by id)