SQL问题，急

[sdweihailh]

列A 列B 列C 列D

80 80 90 列A列B
90 190 90 列A列C
70 70 70 列A列B列C
80 90 100 列A

列D是取列A，列B，列D的最小值的列名进行合并,如果有相同的值，则取满足最小值的列进行合并。
列D怎么写语句出来

[dawugui]

--使用union all将表数据转换,然后用下面的进行合并.

/*
标题：按某字段合并字符串之一(简单合并)
作者：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)
时间：2008-11-06
地点：广东深圳

描述：将如下形式的数据按id字段合并value字段。
id    value
----- ------
1     aa
1     bb
2     aaa
2     bbb
2     ccc
需要得到结果：
id     value
------ -----------
1      aa,bb
2      aaa,bbb,ccc
即：group by id, 求 value 的和（字符串相加）
*/
--1、sql2000中只能用自定义的函数解决
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go

create function dbo.f_str(@id int) returns varchar(100)
as
begin
    declare @str varchar(1000)
    set @str = ''
    select @str = @str + ',' + cast(value as varchar) from tb where id = @id
    set @str = right(@str , len(@str) - 1)
    return @str
end
go

--调用函数
select id , value = dbo.f_str(id) from tb group by id

drop function dbo.f_str
drop table tb


--2、sql2005中的方法
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go

select id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')
from tb
group by id

drop table tb


--3、使用游标合并数据
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
declare @t table(id int,value varchar(100))--定义结果集表变量
--定义游标并进行合并处理
declare my_cursor cursor local for
select id , value from tb
declare @id_old int , @id int , @value varchar(10) , @s varchar(100)
open my_cursor
fetch my_cursor into @id , @value
select @id_old = @id , @s=''
while @@FETCH_STATUS = 0
begin
    if @id = @id_old
       select @s = @s + ',' + cast(@value as varchar)
    else
      begin
        insert @t values(@id_old , stuff(@s,1,1,''))
        select @s = ',' + cast(@value as varchar) , @id_old = @id
      end
    fetch my_cursor into @id , @value
END
insert @t values(@id_old , stuff(@s,1,1,''))
close my_cursor
deallocate my_cursor

select * from @t
drop table tb

[dawugui]

create table tb(id int, A int, B int, C int)
insert into tb values(1 , 80,  80  ,90)
insert into tb values(2 , 90,  190 ,90)
insert into tb values(3 , 70,  70  ,70)
insert into tb values(4 , 80,  90  ,100)
go

--将查询出来的数据先放入一个临时表
select * into tmp from 
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) m where A = (select min(A) from
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) n where n.id = m.id
)

go
create function dbo.f_str(@id int) returns varchar(100)
as
begin
    declare @str varchar(1000)
    set @str = ''
    select @str = @str + ',' + cast(A as varchar) from tmp where id = @id
    set @str = right(@str , len(@str) - 1)
    return @str
end
go

--调用函数
select id , A = dbo.f_str(id) from tmp group by id

drop function dbo.f_str

drop table tb , tmp

/*
id          A                                                                                                    
----------- ---------------------------------------------------------------------------------------------------- 
1           80,80
2           90,90
3           70,70,70
4           80

（所影响的行数为 4 行）
*/

[csdyyr]

SQL code问题描述：
无论是在sql 2000，还是在 sql 2005 中,都没有提供字符串的聚合函数，
  所以，当我们在处理下列要求时，会比较麻烦：
有表tb, 如下：
id    value
----- ------
1     aa
1     bb
2     aaa
2     bbb
2     ccc
需要得到结果：
id     values
------ -----------
1      aa,bb
2      aaa,bbb,ccc
即， group by id, 求 value 的和（字符串相加）

1. 旧的解决方法

-- 1. 创建处理函数
CREATE FUNCTION dbo.f_str(@id int)
RETURNS varchar(8000)
AS
BEGIN
    DECLARE @r varchar(8000)
    SET @r = ''
    SELECT @r = @r + ',' + value
    FROM tb
    WHERE id=@id
    RETURN STUFF(@r, 1, 1, '')
END
GO
-- 调用函数

SELECt id, values=dbo.f_str(id) 
FROM tb 
GROUP BY id

-- 2. 新的解决方法 
-- 示例数据
DECLARE @t TABLE(id int, value varchar(10))
INSERT @t SELECT 1, 'aa'
UNION ALL SELECT 1, 'bb'
UNION ALL SELECT 2, 'aaa'
UNION ALL SELECT 2, 'bbb'
UNION ALL SELECT 2, 'ccc'

-- 查询处理
SELECT *
FROM(
    SELECT DISTINCT 
        id
    FROM @t
)A
OUTER APPLY(
    SELECT 
        [values]= STUFF(REPLACE(REPLACE(
            (
                SELECT value FROM @t N
                WHERE id = A.id
                FOR XML AUTO
            ), '<N value="', ','), '"/>', ''), 1, 1, '')
)N

/*--结果
id          values
----------- ----------------
1           aa,bb
2           aaa,bbb,ccc
(2 行受影响)
--*/

--各种字符串分函数

--3.3.1 使用游标法进行字符串合并处理的示例。
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3

--合并处理
--定义结果集表变量
DECLARE @t TABLE(col1 varchar(10),col2 varchar(100))

--定义游标并进行合并处理
DECLARE tb CURSOR LOCAL
FOR
SELECT col1,col2 FROM tb ORDER BY  col1,col2
DECLARE @col1_old varchar(10),@col1 varchar(10),@col2 int,@s varchar(100)
OPEN tb
FETCH tb INTO @col1,@col2
SELECT @col1_old=@col1,@s=''
WHILE @@FETCH_STATUS=0
BEGIN
    IF @col1=@col1_old
        SELECT @s=@s+','+CAST(@col2 as varchar)
    ELSE
    BEGIN
        INSERT @t VALUES(@col1_old,STUFF(@s,1,1,''))
        SELECT @s=','+CAST(@col2 as varchar),@col1_old=@col1
    END
    FETCH tb INTO @col1,@col2
END
INSERT @t VALUES(@col1_old,STUFF(@s,1,1,''))
CLOSE tb
DEALLOCATE tb
--显示结果并删除测试数据
SELECT * FROM @t
DROP TABLE tb
/*--结果
col1       col2
---------- -----------
a          1,2
b          1,2,3
--*/
GO


/*==============================================*/


--3.3.2 使用用户定义函数，配合SELECT处理完成字符串合并处理的示例
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3
GO

--合并处理函数
CREATE FUNCTION dbo.f_str(@col1 varchar(10))
RETURNS varchar(100)
AS
BEGIN
    DECLARE @re varchar(100)
    SET @re=''
    SELECT @re=@re+','+CAST(col2 as varchar)
    FROM tb
    WHERE col1=@col1
    RETURN(STUFF(@re,1,1,''))
END
GO

--调用函数
SELECT col1,col2=dbo.f_str(col1) FROM tb GROUP BY col1
--删除测试
DROP TABLE tb
DROP FUNCTION f_str
/*--结果
col1       col2
---------- -----------
a          1,2
b          1,2,3
--*/
GO

/*==============================================*/


--3.3.3 使用临时表实现字符串合并处理的示例
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3

--合并处理
SELECT col1,col2=CAST(col2 as varchar(100)) 
INTO #t FROM tb
ORDER BY col1,col2
DECLARE @col1 varchar(10),@col2 varchar(100)
UPDATE #t SET 
    @col2=CASE WHEN @col1=col1 THEN @col2+','+col2 ELSE col2 END,
    @col1=col1,
    col2=@col2
SELECT * FROM #t
/*--更新处理后的临时表
col1       col2
---------- -------------
a          1
a          1,2
b          1
b          1,2
b          1,2,3
--*/
--得到最终结果
SELECT col1,col2=MAX(col2) FROM #t GROUP BY col1
/*--结果
col1       col2
---------- -----------
a          1,2
b          1,2,3
--*/
--删除测试
DROP TABLE tb,#t
GO


/*==============================================*/

--3.3.4.1 每组 <=2 条记录的合并
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'c',3

--合并处理
SELECT col1,
    col2=CAST(MIN(col2) as varchar)
        +CASE 
            WHEN COUNT(*)=1 THEN ''
            ELSE ','+CAST(MAX(col2) as varchar)
        END
FROM tb
GROUP BY col1
DROP TABLE tb
/*--结果
col1       col2      
---------- ----------
a          1,2
b          1,2
c          3
--*/

--3.3.4.2 每组 <=3 条记录的合并
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3
UNION ALL SELECT 'c',3

--合并处理
SELECT col1,
    col2=CAST(MIN(col2) as varchar)
        +CASE 
            WHEN COUNT(*)=3 THEN ','
                +CAST((SELECT col2 FROM tb WHERE col1=a.col1 AND col2 NOT IN(MAX(a.col2),MIN(a.col2))) as varchar)
            ELSE ''
        END
        +CASE 
            WHEN COUNT(*)>=2 THEN ','+CAST(MAX(col2) as varchar)
            ELSE ''
        END
FROM tb a
GROUP BY col1
DROP TABLE tb
/*--结果
col1       col2
---------- ------------
a          1,2
b          1,2,3
c          3
--*/
GO
if not object_id('A') is null
    drop table A
Go
Create table A([id] int,[cname] nvarchar(2))
Insert A
select 1,N'张三' union all
select 2,N'李四' union all
select 3,N'王五' union all
select 4,N'蔡六'
Go
--> --> 
 
if not object_id('B') is null
    drop table B
Go
Create table B([id] int,[cname] nvarchar(5))
Insert B
select 1,N'1,2,3' union all
select 2,N'3,4'
Go
create function F_str(@cname nvarchar(100))
returns nvarchar(100)
as
begin 
select @cname=replace(@cname,ID,[cname]) from A where patindex('%,'+rtrim(ID)+',%',','+@cname+',')>0
return @cname
end
go
select [id],dbo.F_str([cname])[cname] from B

id          cname
----------- ----------------------------------------------------------------------------------------------------
1           张三,李四,王五
2           王五,蔡六

(2 個資料列受到影響)

[csdyyr]

取n列中的最大最小值:
http://topic.csdn.net/u/20081112/11/db933908-4868-4c17-bf00-abc759e174a1.html

[dawugui]

--不用临时表的办法.
create table tb(id int, A int, B int, C int)
insert into tb values(1 , 80,  80  ,90)
insert into tb values(2 , 90,  190 ,90)
insert into tb values(3 , 70,  70  ,70)
insert into tb values(4 , 80,  90  ,100)
go
create function dbo.f_str(@id int) returns varchar(100)
as
begin
    declare @str varchar(1000)
    set @str = ''
    select @str = @str + ',' + cast(A as varchar) from 
(
select * from 
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) m where A = (select min(A) from
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) n where n.id = m.id
)

) t where id = @id
    set @str = right(@str , len(@str) - 1)
    return @str
end
go

--调用函数
select id , A = dbo.f_str(id) from 
(
select * from 
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) m where A = (select min(A) from
(
select id , A from tb
union all
select id , B from tb
union all
select id , C from tb
) n where n.id = m.id
)
) t group by id

drop function dbo.f_str

drop table tb

/*
id          A                                                                                                    
----------- ---------------------------------------------------------------------------------------------------- 
1           80,80
2           90,90
3           70,70,70
4           80

（所影响的行数为 4 行）
*/

[sdweihailh]

列D是取的列A的字段名，不是字段值

[dawugui]

[Quote=引用 6 楼 linhui780705 的回复:]
列D是取的列A的字段名，不是字段值
[/Quote]

--不用临时表的办法.
create table tb(id int, A int, B int, C int)
insert into tb values(1 , 80,  80  ,90)
insert into tb values(2 , 90,  190 ,90)
insert into tb values(3 , 70,  70  ,70)
insert into tb values(4 , 80,  90  ,100)
go
create function dbo.f_str(@id int) returns varchar(100)
as
begin
    declare @str varchar(1000)
    set @str = ''
    select @str = @str + ',' + cast(item as varchar) from 
(
select * from 
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) m where A = (select min(A) from
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) n where n.id = m.id
)

) t where id = @id
    set @str = right(@str , len(@str) - 1)
    return @str
end
go

--调用函数
select id , item = dbo.f_str(id) from 
(
select * from 
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) m where A = (select min(A) from
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) n where n.id = m.id
)
) t group by id

drop function dbo.f_str

drop table tb

/*
id          item                                                                                                 
----------- ---------------------------------------------------------------------------------------------------- 
1           A,B
2           A,C
3           A,B,C
4           A

（所影响的行数为 4 行）

*/

[dawugui]

--不用临时表的办法.
create table tb(id int, A int, B int, C int)
insert into tb values(1 , 80,  80  ,90)
insert into tb values(2 , 90,  190 ,90)
insert into tb values(3 , 70,  70  ,70)
insert into tb values(4 , 80,  90  ,100)
go
create function dbo.f_str(@id int) returns varchar(100)
as
begin
    declare @str varchar(1000)
    set @str = ''
    select @str = @str + ',' + cast(item as varchar) from 
(
select * from 
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) m where A = (select min(A) from
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) n where n.id = m.id
)

) t where id = @id
    set @str = right(@str , len(@str) - 1)
    return @str
end
go

--调用函数
select t1.* , t2.D from tb t1 ,
(
select id , D = dbo.f_str(id) from 
(
select * from 
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) m where A = (select min(A) from
(
select id , A , 'A' item from tb
union all
select id , B , 'B' item from tb
union all
select id , C , 'C' item from tb
) n where n.id = m.id
)
) t group by id
) t2
where t1.id = t2.id

drop function dbo.f_str

drop table tb

/*
id          A           B           C           D                                                                                                    
----------- ----------- ----------- ----------- ---------------------------------------------------------------------------------------------------- 
1           80          80          90          A,B
2           90          190         90          A,C
3           70          70          70          A,B,C
4           80          90          100         A

（所影响的行数为 4 行）

*/

[csdyyr]

CREATE TABLE TB(COL1 INT, COL2 INT, COL3 INT)
INSERT TB
SELECT 80,  80,  90 UNION ALL 
SELECT 90,  190,  90 UNION ALL 
SELECT 70,  70,  70 UNION ALL 
SELECT 80,  90,  100

SELECT COL1,COL2,COL3,
	COL4=(CASE WHEN COL1=MINVAL THEN 'COL1' ELSE '' END+
	              CASE WHEN COL2=MINVAL THEN 'COL2' ELSE '' END+
 	             CASE WHEN COL3=MINVAL THEN  'COL3' ELSE '' END)
FROM (
SELECT *,MINVAL=(SELECT MIN(COL1) FROM 
(SELECT COL1 UNION ALL
SELECT COL2 UNION ALL 
SELECT COL3) T)
FROM TB
) T

DROP TABLE TB
/*
COL1        COL2        COL3        COL4         
----------- ----------- ----------- ------------ 
80          80          90          COL1COL2
90          190         90          COL1COL3
70          70          70          COL1COL2COL3
80          90          100         COL1
*/