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)
--*/CSDN 社区帖子地址 附: 合并与分拆的CLR, sql2005的示例中有:
在安装sql 2005的示例后,默认安装目录为
drive:\Program Files\Microsoft SQL Server\90\Samples\Engine\Programmability\CLR\StringUtilities中
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)
--*/CSDN 社区帖子地址 附: 合并与分拆的CLR, sql2005的示例中有:
在安装sql 2005的示例后,默认安装目录为
drive:\Program Files\Microsoft SQL Server\90\Samples\Engine\Programmability\CLR\StringUtilities中
http://www.windbi.com/showtopic-1480.aspx
if object_id('[T]') is not null drop table [T]
create table [T] ([JoinId] varchar(2),[PxInfoId] varchar(3),[A0101] varchar(7))
insert into [T]
select '01','001','王静' union all
select '01','001','Founsys' union all
select '01','001','xiao' union all
select '02','002','王海'
--select * from T
go
--Code--SQL2000用函数
create function f_str
(@a varchar(10))
returns varchar(100)
as
begin
declare @s varchar(100)
select @s = isnull(@s + ',' ,'') +[A0101] from T where [JoinId] = @a
return @s
end
goselect distinct [JoinId],[A0101]=dbo.f_str([JoinId])
from T
--SQL2005用XML
select distinct [JoinId],
[value]=STUFF((select ','+[A0101] from T where [JoinId]=A.[JoinId] for XML path('')),1,1,'')
FROM T A
--Drop
drop table T
drop function f_str
--Result
/*
JoinId A0101
------ --------------------
01 王静,Founsys,xiao
02 王海(2 行受影响)
*/
create function fn_A0101 (
@JoinId int
)
returns varchar(100)
as
begin
declare @r varchar(100)
select @r=isnull(@r+',','')+A0101 from PxJionedPeople where JoinId =@JoinId
return @r
end
go--查询
select JoinId ,dbo.fn_A0101 (JoinId) as A0101
from PxJionedPeople
group by JoinId
RETURNS varchar(8000)
AS
BEGIN
DECLARE @r varchar(8000)
SET @r = ''
SELECT @r = @r + ',' + A0101
FROM [PxJionedPeople]
WHERE PxInfoId =@PxInfoId
RETURN STUFF(@r, 1, 1, '')
END
GO
--調用函數
select JoinId , PxInfoId ,dbo.f_str(PxInfoId) from [PxJionedPeople] group by JoinId , PxInfoId
create function f_hb(@JoinId int)
returns varchar(8000)
as
begin
declare @str varchar(8000)
set @str = ''
select @str = @str + ',' + cast(A0101 as varchar) from tb where JoinId = @JoinId
set @str = right(@str , len(@str) - 1)
return(@str)
End
go--调用自定义函数得到结果:
select distinct JoinId ,dbo.f_hb(JoinId) as A0101 from tb
select JoinId, [A0101]=stuff((select ','+[A0101] from tb t where JoinId=tb.JoinId for xml path('')), 1, 1, '')
from tb
group by JoinId