--按某一字段分组取最大(小)值所在行的数据
--(爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开) 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)
*/
-- Author: liangCK 小梁
-- Date : 2008-11-14 20:33:23
---------------------------------
--> 生成测试数据: @T
DECLARE @T TABLE (id INT,p_id INT,p_date DATETIME)
INSERT INTO @T
SELECT 1,1,'2008-12-01 1:00:00' UNION ALL
SELECT 2,2,'2008-12-01 2:00:00' UNION ALL
SELECT 3,3,'2008-12-01 1:00:00' UNION ALL
SELECT 4,4,'2008-12-01 1:00:00' UNION ALL
SELECT 5,1,'2008-12-01 2:00:00' UNION ALL
SELECT 6,1,'2008-12-01 3:00:00' UNION ALL
SELECT 7,2,'2008-12-01 5:00:00' UNION ALL
SELECT 8,3,'2008-12-01 2:00:00' UNION ALL
SELECT 9,4,'2008-12-01 5:00:00' UNION ALL
SELECT 10,4,'2008-12-01 6:00:00' UNION ALL
SELECT 11,4,'2008-12-01 7:00:00'--SQL查询如下:SELECT *
FROM @T AS A
WHERE p_id IN(1,2,4)
AND NOT EXISTS(
SELECT *
FROM(
SELECT *
FROM @T
WHERE p_id IN(1,2,4)
) AS T
WHERE p_id=A.p_id
AND p_date>A.p_date
)/*
id p_id p_date
----------- ----------- -----------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000(3 行受影响)*/
-- Author: liangCK 小梁
-- Date : 2008-11-14 20:33:23
---------------------------------
--> 生成测试数据: @T
DECLARE @T TABLE (id INT,p_id INT,p_date DATETIME)
INSERT INTO @T
SELECT 1,1,'2008-12-01 1:00:00' UNION ALL
SELECT 2,2,'2008-12-01 2:00:00' UNION ALL
SELECT 3,3,'2008-12-01 1:00:00' UNION ALL
SELECT 4,4,'2008-12-01 1:00:00' UNION ALL
SELECT 5,1,'2008-12-01 2:00:00' UNION ALL
SELECT 6,1,'2008-12-01 3:00:00' UNION ALL
SELECT 7,2,'2008-12-01 5:00:00' UNION ALL
SELECT 8,3,'2008-12-01 2:00:00' UNION ALL
SELECT 9,4,'2008-12-01 5:00:00' UNION ALL
SELECT 10,4,'2008-12-01 6:00:00' UNION ALL
SELECT 11,4,'2008-12-01 7:00:00'--SQL查询如下:--2005SELECT
id,
p_id,
p_date
FROM(
SELECT
*,
RID=ROW_NUMBER() OVER(PARTITION BY p_id ORDER BY p_date DESC)
FROM @T
WHERE p_id IN(1,2,4)
) AS A
WHERE RID=1
/*
id p_id p_date
----------- ----------- -----------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000(3 行受影响)
*/
-- Author: liangCK 小梁
-- Date : 2008-11-14 20:33:23
---------------------------------
--> 生成测试数据: T
CREATE TABLE T(id INT,p_id INT,p_date DATETIME)
INSERT INTO T
SELECT 1,1,'2008-12-01 1:00:00' UNION ALL
SELECT 2,2,'2008-12-01 2:00:00' UNION ALL
SELECT 3,3,'2008-12-01 1:00:00' UNION ALL
SELECT 4,4,'2008-12-01 1:00:00' UNION ALL
SELECT 5,1,'2008-12-01 2:00:00' UNION ALL
SELECT 6,1,'2008-12-01 3:00:00' UNION ALL
SELECT 7,2,'2008-12-01 5:00:00' UNION ALL
SELECT 8,3,'2008-12-01 2:00:00' UNION ALL
SELECT 9,4,'2008-12-01 5:00:00' UNION ALL
SELECT 10,4,'2008-12-01 6:00:00' UNION ALL
SELECT 11,4,'2008-12-01 7:00:00'--SQL查询如下:--参数传递GOCREATE PROC p @where varchar(200)
AS
EXEC('
SELECT *
FROM T AS A
WHERE '+@where+'
AND NOT EXISTS(
SELECT *
FROM(
SELECT *
FROM T
WHERE '+@where+'
) AS B
WHERE p_id=A.p_id
AND p_date>A.p_date
)
')
--2005
--EXEC('
--SELECT
--id,
--p_id,
--p_date
--FROM(
--SELECT
--*,
--RID=ROW_NUMBER() OVER(PARTITION BY p_id ORDER BY p_date DESC)
--FROM T
--WHERE '+@where+'
--) AS A
--WHERE RID=1
--')
GOEXEC p '(p_id=1 or p_id =2 or p_id=4)'DROP PROC p
DROP TABLE T/*
id p_id p_date
----------- ----------- -----------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000(3 行受影响)
*/
INSERT INTO @T
SELECT 1,1,'2008-12-01 1:00:00' UNION ALL
SELECT 2,2,'2008-12-01 2:00:00' UNION ALL
SELECT 3,3,'2008-12-01 1:00:00' UNION ALL
SELECT 4,4,'2008-12-01 1:00:00' UNION ALL
SELECT 5,1,'2008-12-01 2:00:00' UNION ALL
SELECT 6,1,'2008-12-01 3:00:00' UNION ALL
SELECT 7,2,'2008-12-01 5:00:00' UNION ALL
SELECT 8,3,'2008-12-01 2:00:00' UNION ALL
SELECT 9,4,'2008-12-01 5:00:00' UNION ALL
SELECT 10,4,'2008-12-01 6:00:00' UNION ALL
SELECT 11,4,'2008-12-01 7:00:00'
select *
from @t t
where not exists(select 1 from @t where p_id =t.p_id and p_date > t.p_date)
and P_id in(1,2,4)/*id p_id p_date
----------- ----------- -----------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000(3 行受影响)
*/
CREATE TABLE #TB(id INT,p_id INT,p_date DATETIME)
INSERT INTO #TB
SELECT 1,1,'2008-12-01 1:00:00' UNION ALL
SELECT 2,2,'2008-12-01 2:00:00' UNION ALL
SELECT 3,3,'2008-12-01 1:00:00' UNION ALL
SELECT 4,4,'2008-12-01 1:00:00' UNION ALL
SELECT 5,1,'2008-12-01 2:00:00' UNION ALL
SELECT 6,1,'2008-12-01 3:00:00' UNION ALL
SELECT 7,2,'2008-12-01 5:00:00' UNION ALL
SELECT 8,3,'2008-12-01 2:00:00' UNION ALL
SELECT 9,4,'2008-12-01 5:00:00' UNION ALL
SELECT 10,4,'2008-12-01 6:00:00' UNION ALL
SELECT 11,4,'2008-12-01 7:00:00'
GOcreate proc Test @A VARCHAR(100)
as
declare @sql varchar(1000);
set @sql = 'select * from #TB a where ('
+ @A
+ ') and not exists(select * from #TB where p_id=a.p_id and p_date>a.p_date)'
print @sql
exec(@sql)
GOexec test 'p_id=1 or p_id =2 or p_id=4'DROP PROC TEST
DROP TABLE #TB/**
select * from #TB a where (p_id=1 or p_id =2 or p_id=4) and not exists(select * from #TB where p_id=a.p_id and p_date>a.p_date)id p_id p_date
----------- ----------- ------------------------------------------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000（所影响的行数为 3 行）
**/
Set Nocount On
if not object_id('test') is null
drop table test
Go
Create table test([id] int,[p_id] int,[p_date] Datetime)
Insert test
select 1,1,'2008-12-01 1:00:00' union all
select 2,2,'2008-12-01 2:00:00' union all
select 3,3,'2008-12-01 1:00:00' union all
select 4,4,'2008-12-01 1:00:00' union all
select 5,1,'2008-12-01 2:00:00' union all
select 6,1,'2008-12-01 3:00:00' union all
select 7,2,'2008-12-01 5:00:00' union all
select 8,3,'2008-12-01 2:00:00' union all
select 9,4,'2008-12-01 5:00:00' union all
select 10,4,'2008-12-01 6:00:00' union all
select 11,4,'2008-12-01 7:00:00'
Go
--根据(id为自动递增) ，可以参考：If Object_id('up_test') Is Not Null
Drop Proc up_test
Go
Create Proc up_test
(@condition nvarchar(4000))
As
Set @condition=Isnull(' And '+@condition,'')
Exec('Select * From test As a Where (1=1 '+@condition+') And id=(Select Max(id) From test Where p_id=a.p_id)')
Go
Exec up_test 'p_id=1 or p_id =2 or p_id=4'
/*id p_id p_date
----------- ----------- -----------------------
6 1 2008-12-01 03:00:00.000
7 2 2008-12-01 05:00:00.000
11 4 2008-12-01 07:00:00.000
*/