合并列值
原著：邹建
改编：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开) 2007-12-16 广东深圳
表结构，数据如下：
| 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）
旧的解决方法(在sql server 2000中只能用函数解决。)
1、方式一
- 创建处理函数
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(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, value = dbo.f_str(id) FROM tb GROUP BY id
drop table tb
drop function dbo.f_str
2、方式二
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
- 创建一个合并的函数
create function f_hb(@id int)
returns varchar(8000)
as
begin
declare @str varchar(8000)
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
- 调用自定义函数得到结果：
select distinct id ,dbo.f_hb(id) as value from tb
drop table tb
drop function dbo.f_hb
新的解决方法(在sql server 2005中用OUTER APPLY等解决。)
1、方式一
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
- 查询处理
SELECT * FROM(SELECT DISTINCT id FROM tb)A OUTER APPLY(
SELECT [values]= STUFF(REPLACE(REPLACE(
(
SELECT value FROM tb N
WHERE id = A.id
FOR XML AUTO
), ' <N value="', ','), '"/>', ''), 1, 1, '')
)N
drop table tb
2、方式2
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, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '')
from tb
group by id
drop table tb
经过实际验证
方法一
select distinct cbsnames =stuff((select ','+sname from [cbs_sort] t where id in (1,2,4) for xml path('')), 1, 1, '')
from [cbs_sort]
方法二：
select top 1 namelist=STUFF(REPLACE(REPLACE(( SELECT sname FROM [cbs_sort] where id in (1,2,3,4)
FOR XML AUTO ), '<cbs_sort sname="', ','), '"/>', ''), 1, 1, '')
from [cbs_sort]
