在SQL中分类合并数据行[转至 dobear]

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-- =============================================================================-- Title: 在SQL中分类合并数据行-- Author: dobear Mail(MSN): dobear_0922@hotmail.com-- Environment: Vista + SQL2005-- Date: 2008-04-22-- =============================================================================--1. 创建表，添加测试数据CREATE TABLE tb(id int, [value] varchar(10))INSERT tb SELECT 1, 'aa'UNION ALL SELECT 1, 'bb'UNION ALL SELECT 2, 'aaa'UNION ALL SELECT 2, 'bbb'UNION ALL SELECT 2, 'ccc'--SELECT * FROM tb/**//*id value----------- ----------1 aa1 bb2 aaa2 bbb2 ccc(5 row(s) affected)*/--2 在SQL2000只能用自定义函数实现----2.1 创建合并函数fn_strSum，根据id合并value值GOCREATE FUNCTION dbo.fn_strSum(@id int)RETURNS varchar(8000)ASBEGIN DECLARE @values varchar(8000) SET @values = '' SELECT @values = @values + ',' + value FROM tb WHERE id=@id RETURN STUFF(@values, 1, 1, '')ENDGO-- 调用函数SELECT id, VALUE = dbo.fn_strSum(id) FROM tb GROUP BY idDROP FUNCTION dbo.fn_strSum----2.2 创建合并函数fn_strSum2，根据id合并value值GOCREATE FUNCTION dbo.fn_strSum2(@id int)RETURNS varchar(8000)ASBEGIN DECLARE @values varchar(8000) SELECT @values = isnull(@values + ',', '') + value FROM tb WHERE id=@id RETURN @valuesENDGO-- 调用函数SELECT id, VALUE = dbo.fn_strSum2(id) FROM tb GROUP BY idDROP FUNCTION dbo.fn_strSum2--3 在SQL2005中的新解法----3.1 使用OUTER APPLYSELECT * 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----3.2 使用XMLSELECT id, [values]=STUFF((SELECT ','+[value] FROM tb t WHERE id=tb.id FOR XML PATH('')), 1, 1, '')FROM tbGROUP BY id--4 删除测试表tbdrop table tb/**//*id values----------- --------------------1 aa,bb2 aaa,bbb,ccc(2 row(s) affected)*/