SqlServer：多行合并成一行，并做分组统计的两个方法

CREATE TABLE test(code varchar(50), [values] varchar(10),[count] int)
INSERT test SELECT '001', 'aa',1
UNION ALL SELECT '001', 'bb',2
UNION ALL SELECT '002', 'aaa',4
UNION ALL SELECT '002', 'bbb',5
UNION ALL SELECT '002', 'ccc',3;

--方法一
--将多行合并成一行，并做分组统计
SELECT code,
       [values] =
       stuff(b.[values].value('/R[1]', 'nvarchar(max)'),
,
,
             ''),[count]
  FROM (SELECT  code,sum([count]) as [count]
          FROM test
         GROUP BY code) a
 CROSS apply (
        SELECT [values] =(
            SELECT N',' + [values] FROM test
              WHERE code = a.code
                         FOR XML PATH(''), ROOT('R'), TYPE
        )
) b;

--方法二

---SQL2005中的新解法   使用XML

SELECT code, data=STUFF((SELECT ','+[values] FROM test t WHERE code=t1.code FOR XML PATH('')), 1, 1, ''),sum([count]) as [count]
FROM test t1
GROUP BY code

--查询结果

--001    aa,bb    3
--002    aaa,bbb,ccc    12

drop table test

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