sql多行归并查询

 发表于：2008-10-29 10:59:201楼 得分:0 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     aa1     bb2     aaa2     bbb2     ccc需要得到结果：id     values------ -----------1      aa,bb2      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)ASBEGIN    DECLARE @r varchar(8000)    SET @r = ''    SELECT @r = @r + ',' + value    FROM tb    WHERE id=@id    RETURN STUFF(@r, 1, 1, '')ENDGO-- 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)AOUTER 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,bb2           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
------解决方案--------------------
SQL code
/*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     aa1     bb2     aaa2     bbb2     ccc需要得到结果：id     value------ -----------1      aa,bb2      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')gocreate function dbo.f_str(@id int) returns varchar(100)asbegin    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 @strendgo--调用函数select id , value = dbo.f_str(id) from tb group by iddrop function dbo.f_strdrop 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')goselect id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')from tbgroup by iddrop 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')godeclare @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 forselect id , value from tbdeclare @id_old int , @id int , @value varchar(10) , @s varchar(100)open my_cursorfetch my_cursor into @id , @valueselect @id_old = @id , @s=''while @@FETCH_STATUS = 0begin    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 , @valueENDinsert @t values(@id_old , stuff(@s,1,1,''))close my_cursordeallocate my_cursorselect * from @tdrop table tb