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
--> 生成测试数据: #T
IF OBJECT_ID('tempdb.dbo.#T') IS NOT NULL DROP TABLE #T
CREATE TABLE #T (s0 INT,s1 VARCHAR(1),s2 INT,s3 SQL_VARIANT)
INSERT INTO #T
SELECT '1001','a','22',null UNION ALL
SELECT '1001','b','33',null UNION ALL
SELECT '1001','d','33',null UNION ALL
SELECT '1002','c','44',null--SQL查询如下:SELECT s0,
CAST(STUFF((SELECT '/'+s1
FROM #T
WHERE s0=t.s0
FOR XML PATH(''))
,1,1,'') AS VARCHAR(20)) AS s1,
CAST(STUFF((SELECT ','+RTRIM(s2)
FROM #T
WHERE s0=t.s0
FOR XML PATH(''))
,1,1,'') AS VARCHAR(20)) AS s2,
CAST(STUFF((SELECT ','+s1+':'+RTRIM(s2)
FROM #T
WHERE s0=t.s0
FOR XML PATH(''))
,1,1,'') AS VARCHAR(20)) AS s3
FROM #T AS t
GROUP BY s0/*
s0 s1 s2 s3
----------- -------------------- -------------------- --------------------
1001 a/b/d 22,33,33 a:22,b:33,d:33
1002 c 44 c:44(2 行受影响)*/
--> 测试数据: [s]
if object_id('[s]') is not null drop table [s]
create table [s] (s0 int,s1 varchar(1),s2 int,s3 sql_variant)
insert into [s]
select 1001,'a',22,null union all
select 1001,'b',33,null union all
select 1001,'d',33,null union all
select 1002,'c',44,null--创建合并函数
create function fs(@s0 int,@type int)
returns varchar(500)
as
begin
declare @sql varchar(500)
select @sql=isnull(@sql+case @type when 3 then ',' else '/' end,'')+
case @type when 1 then ltrim(s1) when 2 then ltrim(s2) when 3 then s1+':'+ltrim(s2) end
from s where s0=@s0
return @sql
end
goselect distinct s0,s1=dbo.fs(s0,1),s2=dbo.fs(s0,2),s3=dbo.fs(s0,3) from [s]
CREATE TABLE tb (s0 INT,s1 VARCHAR(1),s2 INT,s3 varchar(1000))
INSERT INTO tb
SELECT '1001','a','22',null UNION ALL
SELECT '1001','b','33',null UNION ALL
SELECT '1001','d','33',null UNION ALL
SELECT '1002','c','44',null
--select * from tb
--drop table tbselect s0
,s1=stuff((select '/'+s1 from tb where s0=t.s0 for xml path('')),1,1,'')
,s2=stuff((select '/'+rtrim(s2) from tb where s0=t.s0 group by s2 for xml path('')),1,1,'')
,s3=case when count(1)>1 then stuff((select ','+s1+':'+rtrim(s2) from tb where s0=t.s0 for xml path('')),1,1,'') else '' end
from tb t
group by s0/*
s0 s1 s2 s3
--------------------------------
1001 a/b/d 22/33 a:22,b:33,d:33
1002 c 44
*/
if object_id('[s]') is not null drop table [s]
create table [s] (s0 int,s1 varchar(1),s2 int,s3 sql_variant)
insert into [s]
select 1001,'a',22,null union all
select 1001,'b',33,null union all
select 1001,'d',33,null union all
select 1002,'c',44,null--创建合并函数
create function fs(@s0 int,@type int)
returns varchar(500)
as
begin
declare @sql varchar(500)
select @sql=isnull(@sql+case @type when 3 then ',' else '/' end,'')+
case @type when 1 then ltrim(s1) when 2 then ltrim(s2) when 3 then s1+':'+ltrim(s2) end
from s where s0=@s0
return @sql
end
goselect distinct s0,s1=dbo.fs(s0,1),s2=dbo.fs(s0,2),s3=dbo.fs(s0,3) from [s]
CREATE FUNCTION dbo.f_str(@id int)
RETURNS varchar(8000)
AS
BEGIN
DECLARE @r varchar(8000)
SET @r = ''
SELECT @r = @r + ',' + value FROM t WHERE id=@id
RETURN STUFF(@r, 1, 1, '')
END
GOSELECt id, values=dbo.f_str(id)
FROM tb
GROUP BY id
可以满足你的要求,我用过