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求一条关于max的语句

greatlsd 2008-03-12 03:19:04
表如下:
id code row1 row2
1 1 33 a
2 1 44 b
3 2 55 c
4 2 66 d
5 2 22 e
6 3 11 f
7 3 99 g

要求输出:

id code row1 row2
2 1 44 b
4 2 66 d
7 3 99 g

即把code相同的、并且row1值最大的一行筛选出来
多谢
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FAFA_2007 2008-03-12

CREATE TABLE fa(ID varchar(10),name varchar(10),op varchar(10),qt int)
INSERT fa SELECT 'fa12','发','同意1',123
UNION ALL SELECT 'fa12','发','同意2',321
UNION ALL SELECT 'fa12','发','同意3',213
UNION ALL SELECT 'fa22','发','同意1',231

select a.* from fa a ,(select id1,max(qt)qt from fa group by id1)b
where a.id1=b.id1 and a.qt=b.qt
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dawugui 2008-03-12
create table tb(id int,   code int,   row1 varchar(10),   row2 varchar(10))
insert into tb values(1, 1, '33', 'a')
insert into tb values(2, 1, '44', 'b')
insert into tb values(3, 2, '55', 'c')
insert into tb values(4, 2, '66', 'd')
insert into tb values(5, 2, '22', 'e')
insert into tb values(6, 3, '11', 'f')
insert into tb values(7, 3, '99', 'g')
go

--方法1:
select t.* from tb t where row1 = (select max(row1) from tb where code = t.code) order by t.id
--方法2:
select t.* from tb t where not exists(select 1 from tb where code = t.code and row1 > t.row1) order by t.id
--方法3:
select t.* from tb t ,(select code,max(row1) row1 from tb group by code) b where t.code= b.code and t.row1 = b.row1 order by t.id
--方法4:
select t.* from tb t inner join (select code, max(row1) row1 from tb group by code) b on t.code= b.code and t.row1 = b.row1 order by t.id
--方法5
select t.* from tb t where 1 > (select count(*) from tb where code = t.code and row1 > t.row1 ) order by t.id

drop table tb

/*
id code row1 row2
----------- ----------- ---------- ----------
2 1 44 b
4 2 66 d
7 3 99 g

(所影响的行数为 3 行)
*/
回复

select t1.id,t1.code,t1.row1,t1.row2 from t1
inner join
(select code, max(row1) as row1 from t1
group by code) as t2 on t1.code = t2.code and t2.row1 = t1.row1
order by t1.code
回复
dobear_0922 2008-03-12
select * 
from TA a
where not exists(select 1 from ta where code = a.code and row1 > a.row1)
回复
dawugui 2008-03-12
create table tb(id int,   code int,   row1 varchar(10),   row2 varchar(10))
insert into tb values(1, 1, '33', 'a')
insert into tb values(2, 1, '44', 'b')
insert into tb values(3, 2, '55', 'c')
insert into tb values(4, 2, '66', 'd')
insert into tb values(5, 2, '22', 'e')
insert into tb values(6, 3, '11', 'f')
insert into tb values(7, 3, '99', 'g')
go

select t.* from tb t where row1 = (select max(row1) from tb where code = t.code) order by t.id

drop table tb

/*
id code row1 row2
----------- ----------- ---------- ----------
2 1 44 b
4 2 66 d
7 3 99 g

(所影响的行数为 3 行)
*/
回复
JiangHongTao 2008-03-12
select * 
from TA a
where not exists
(select 1 from ta where code = a.code and (row1 > a.row1 or (row1=a.row1 and id > a.id)))
回复
wzy_love_sly 2008-03-12
select * from tb a
where not exists(select 1 from tb where code = a.code and row1 > a.row1)
回复
JiangHongTao 2008-03-12
select * 
from TA a
where not exists
(select 1 from ta where code = a.code and (row1 > a.row1 or row1=a.row1 and id > a.id))
回复
JiangHongTao 2008-03-12
select * 
from TA a
where not exists
(select 1 from ta where code = a.code and (row1 > a.row1 or row1=a.row1 and id > a.id)
回复
dawugui 2008-03-12
--按某一字段分组取最大(小)值所在行的数据
(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')
go

select * , px = identity(int,1,1) into tmp from tb

select 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')
go

select 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)
*/
回复
-狙击手- 2008-03-12
select *
from TA a
where not exists(select 1 from ta where code = a.code and row1 > a.row1)
回复
fcuandy 2008-03-12
楼主看看, 自己把表名和字段名替换下就可以了.写法太多,我不写了.


http://topic.csdn.net/u/20080123/18/9731d130-0d4b-4c11-8d89-f2c3ca331f0c.html
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创建于2007-09-28

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