如何选出每个组中满足条件的第一条？

[firevian]

表中有如下数据。

ID Name Data
1 AAA 数据1
2 AAA 数据2
3 AAA NULL
4 AAA NULL
5 AAA NULL
6 BBB 数据3
7 BBB NULL
8 BBB NULL
9 CCC 数据4
10 CCC 数据5
11 CCC 数据6
12 CCC NULL

Name相同的行是一组数据，现在要取出每组数据中为NULL的第一条记录.
这个例子里取出的数据就是
3 AAA NULL
7 BBB NULL
12 CCC NULL

怎么做？高手请指点 多谢多谢！

[ai_li7758521]

--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,a.val
/*
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 , a.val
/*
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)
*/

[ai_li7758521]

DECLARE @T table([ID] int,[Name] varchar(10),[Data] varchar(10),[排序1] varchar(10),[排序2] varchar(10))
INSERT @T
SELECT 1,'AAA',		'数据1',	'0010',	'V'	UNION ALL
SELECT 2,'AAA',		'数据2',	'0010',	'W'	UNION ALL
SELECT 3,'AAA',		NULL,		'0010',	'Y'	UNION ALL
SELECT 4,'AAA',		NULL,		'0010',	'X'	UNION ALL
SELECT 5,'AAA',		NULL,		'0010',	'Z'	UNION ALL
SELECT 6,'BBB',		'数据3',	'0010',	'Z'	UNION ALL
SELECT 7,'BBB',		NULL,		'0020',	'Z' UNION ALL
SELECT 8,'BBB',		NULL,		'0020',	'Y'	UNION ALL
SELECT 9,'CCC',		'数据4',	'0010',	'Z'	UNION ALL
SELECT 10,'CCC',	'数据5',	'0020',	'X'	UNION ALL
SELECT 11,'CCC',	'数据6',	'0020',	'Y'	UNION ALL
SELECT 12,'CCC',	NULL,		'0020',	'Z'

---------------------------------------------------
SELECT [ID],[Name],[Data] 
FROM @T A 
WHERE ID IN 
	(
		SELECT TOP 1 ID FROM @T 
		WHERE [Name]=A.[Name] AND [Data] IS NULL 
		ORDER BY 排序1,排序2 ASC
	)

ID          Name       Data
----------- ---------- ----------
4           AAA        NULL
8           BBB        NULL
12          CCC        NULL

(3 行受影响)

[Tomzzu]

有ID字段了, 就不用排序了

select z.*
	from 表名 as z,
	(select min(id) as id
		from 表名
		where data is null
		group by name	
	) as m
	where z.id = m.id

[xuejie09242]

select * from tableName where id in
  (select min(id) from tableName where data is null group by name )

[firevian]

有时候真的觉的自己是否适合编程 脑子有时候转不过弯
select * from tb t where id=(select top 1 id from tb where name=t.name and data is null order by 排序1,排序2 ASC)

多谢各位大大。特别是htl258。结贴给分。顶者有份。

谢谢!

[jiangshun]

select * from tb where not exist(selet 1 from tb t where t.name=name and t.ID<ID) and Data is null

[olddown]

select min(ID) as ID,Name,Data from temp where Data is null group by Name,Data

[htl258_Tony]

if object_id('[tb]') is not null drop table [tb] 
 go 
create table [tb]([ID] int,[Name] varchar(10),[Data] varchar(10))
insert [tb] select 1,'AAA','数据1'
union all select 2,'AAA','数据2'
union all select 3,'AAA',NULL
union all select 4,'AAA',NULL
union all select 5,'AAA',NULL
union all select 6,'BBB','数据3'
union all select 7,'BBB',NULL
union all select 8,'BBB',NULL
union all select 9,'CCC','数据4'
union all select 10,'CCC','数据5'
union all select 11,'CCC','数据6'
union all select 12,'CCC',NULL
go
select * from tb t where id=(select min(id) from tb where name=t.name and data is null)
/*
ID          Name       Data
----------- ---------- ----------
3           AAA        NULL
7           BBB        NULL
12          CCC        NULL

(3 行受影响)

*/

[jiangshun]

select min(ID),Name,Data from tb where Data is null group by Name,Data

[--小F--]

select * from tb t where id=(select min(id) from tb where name=t.name and data is null)

[nalnait]

[Quote=引用 4 楼 jiangshun 的回复:]
SQL codeselect min(ID),Name,Data from tb where Data is null group by Name,Data
[/Quote].

[firevian]

不好意思啊 各位大大 好像大家都在id上做文章，组中的排序不是按id来的， 我再加两列

ID Name Data 排序1 排序2
1 AAA 数据1 0010 V
2 AAA 数据2 0010 W
3 AAA NULL 0010 Y
4 AAA NULL 0010 X
5 AAA NULL 0010 Z
6 BBB 数据3 0010 Z
7 BBB NULL 0020 Z
8 BBB NULL 0020 Y
9 CCC 数据4 0010 Z
10 CCC 数据5 0020 X
11 CCC 数据6 0020 Y
12 CCC NULL 0020 Z

Name相同的行是一组数据，排序规则是"排序1，排序2 ASC", 现在要取出每组数据中为NULL的第一条记录.
这个例子里取出的数据就是
4 AAA NULL 0010 X
8 BBB NULL 0020 Y
12 CCC NULL 0020 Z

不好意思啊 各位大大再帮帮忙 多谢多谢

[JonasFeng]

select * from LI t where id=(select min([id]) from LI where [name]=t.[name] and data is null)

[feixianxxx]

if object_id('t1')is not null drop table t1
create table t1 (ID int ,Name char(3),Data varchar(100))
insert t1
select 1,'AAA','数据1' union all
select 2,'AAA','数据2' union all
select 3,'AAA',NULL union all
select 4,'AAA',NULL union all
select 5,'BBB','数据3' union all
select 6,'BBB',NULL union all
select 7,'BBB',NULL union all
select 8,'CCC',NULL
select min(ID)as [ID] ,name,Data from t1 where [Data] is null  group by name,Data

[htl258_Tony]

[Quote=引用 7 楼 firevian 的回复:]
不好意思啊 各位大大 好像大家都在id上做文章，组中的排序不是按id来的， 我再加两列

ID Name Data 排序1 排序2
1 AAA 数据1 0010 V
2 AAA 数据2 0010 W
3 AAA NULL 0010 Y
4 AAA NULL 0010 X
5 AAA NULL 0010 Z
6 BBB 数据3 0010 Z
7 BBB NULL 0020 Z
8 BBB NULL 0020 Y
9 CCC 数据4 0010 Z
10 CCC 数据5 0020 X
11 CCC 数据6 002…
[/Quote]

if object_id('[tb]') is not null drop table [tb] 
 go 
create table [tb]([ID] int,[Name] varchar(10),[Data] varchar(10),[排序1] varchar(10),[排序2] varchar(10))
insert [tb] select 1,'AAA','数据1','0010','V'
union all select 2,'AAA','数据2','0010','W'
union all select 3,'AAA',NULL,'0010','Y'
union all select 4,'AAA',NULL,'0010','X'
union all select 5,'AAA',NULL,'0010','Z'
union all select 6,'BBB','数据3','0010','Z'
union all select 7,'BBB',NULL,'0020','Z'
union all select 8,'BBB',NULL,'0020','Y'
union all select 9,'CCC','数据4','0010','Z'
union all select 10,'CCC','数据5','0020','X'
union all select 11,'CCC','数据6','0020','Y'
union all select 12,'CCC',NULL,'0020','Z'
go
select * from tb t where id=(select top 1 id from tb where name=t.name and data is null order by 排序1,排序2 ASC)
/*
ID          Name       Data       排序1        排序2
----------- ---------- ---------- ---------- ----------
4           AAA        NULL       0010       X
8           BBB        NULL       0020       Y
12          CCC        NULL       0020       Z

(3 行受影响)
*/

[--小F--]

select * from tb t where id=(select top 1 id from tb where name=t.name and data is null order by 排序1,排序2 ASC)

[feixianxxx]

[Quote=引用 10 楼 htl258 的回复:]
引用 7 楼 firevian 的回复:
不好意思啊 各位大大 好像大家都在id上做文章，组中的排序不是按id来的， 我再加两列

ID Name Data 排序1 排序2
1 AAA 数据1 0010 V
2 AAA 数据2 0010 W
3 AAA NULL 0010 Y
4 AAA NULL 0010 X
5 AAA NULL 0010 Z
6 BBB 数据3 0010 Z
7 BBB NULL 0020 Z
8 BBB NULL 0020 Y
9 CCC 数据4 0010 Z
10 CCC 数据5 0…
[/Quote]\
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