DB2 合并字段方法

违法℃玩家

　　今天一位以前的同事问起这个问题，以前貌似见过但是忘记了，随即上网查查了
　　参照了这个http://topic.csdn.net/u/20090926/22/43301a7a-00eb-4072-b0c1-c4158ed5a868.html
　　和 http://topic.csdn.net/u/20090925/09/4218b452-9696-4c5c-a687-e0f42196af3b.html
　　原始数据结构如下：
<!--StartFragment -->
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文章名 作者  创建时间  附件名称
春天    程晓锋  2010-9-9  a.doc
春天    程晓锋  2010-9-9  b.doc
春天    程晓锋  2010-9-9  我的.ppt
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　　希望能有一套高效的方法，将其迅速整理成如下格式：
表2
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文章名 作者  创建时间  附件名称
春天    程晓锋  2010-9-9  a.doc, b.doc, 我的.ppt
----------------------------------------------------------
　　CREATE TABLE T_BASE(ID INT,NAME VARCHAR(10),AGE INT);

INSET INTO T_BASE VALUES
(1,'ZHANG',30),
(2,'YANG',28),
(3,'LI',33);
CREATE TABLE T_DETAIL(ID INT,INFO VARCHAR(10));
INSERT INTO T_DETAIL VALUES
(1,'ZHANG1'),
(1,'ZHANG2'),
(1,'ZHANG3'),
(2,'YANG1'),
(2,'YANG2'),
(3,'LI1');

WITH B (FATHER,SON,ID,ALLINFO) AS
    (SELECT  RTRIM(LTRIM(CHAR(A.ID)))|| CHAR(ROW_NUMBER() OVER(PARTITION BY ID)) AS FATHER,
            RTRIM(LTRIM(CHAR(A.ID)))|| CHAR(ROW_NUMBER() OVER(PARTITION BY ID) + 1) AS SON,
            A.ID, CAST(A.INFO AS VARCHAR(100))
    FROM T_DETAIL A
    UNION ALL
    SELECT C.FATHER,C.SON,C.ID,
    RTRIM(LTRIM(B.ALLINFO))||','||RTRIM(LTRIM(CHAR(C.INFO)))
    FROM (SELECT 
    RTRIM(LTRIM(CHAR(A.ID)))|| CHAR(ROW_NUMBER() OVER(PARTITION BY ID)) AS FATHER,
    RTRIM(LTRIM(CHAR(A.ID)))|| CHAR(ROW_NUMBER() OVER(PARTITION BY ID) + 1) AS SON, FROM T_DETAIL A) AS C, B
    WHERE B.SON= C.FATHER)
SELECT  E.ID,E.NAME,E.AGE,D.ALLINFO
FROM (SELECT ROW_NUMBER() OVER(PARTITION BY ID ORDER BY LENGTH(ALLINFO) DESC) AS ROW_NUM, B.ID,B.ALLINFO FROM B) AS D,T_BASE E
WHERE D.ROW_NUM = 1 AND D.ID=E.ID;
　　A.ID, A.INFO
　　===================================================================================
　　*
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
　　
　　家里没有数据库 先保存一下 明天测试一下