示例表 tb 数据如下
id value
—————
1 aa
1 bb
2 aaa
2 bbb
2 ccc
第一种
SELECT id, [val]=( SELECT [value] +',' FROM tb AS b WHERE b.id = a.id FOR XML PATH('') ) FROM tb AS a
第一种显示结果
1 aa,bb,
1 aa,bb,
2 aaa,bbb,ccc,
2 aaa,bbb,ccc,
2 aaa,bbb,ccc,
第二种
SELECT id, [val]=( SELECT [value] +',' FROM tb AS b WHERE b.id = a.id FOR XML PATH('') ) FROM tb AS a GROUP BY id
1 aa,bb,
2 aaa,bbb,ccc,
第三种 (用STUFF函数替换掉首端的逗号)
SELECT id,
[val]=STUFF( (SELECT ','+[value]
FROM tb AS b
WHERE b.id = a.id
FOR XML PATH('')) , 1 , 1 , '' )
FROM tb AS a
GROUP BY id
第三种显示结果
1 aa,bb
2 aaa,bbb,ccc
STUFF 函数将字符串插入另一字符串。它在第一个字符串中从开始位置删除指定长度的字符;然后将第二个字符串插入第一个字符串的开始位置。
STUFF ( character_expression , start , length ,character_expression_insert )
第四种 (用REPLACE函数将所有空格替换成逗号)
SELECT id,
[val]= REPLACE( (SELECT [value] AS [data()]
FROM tb AS b
WHERE b.id = a.id
FOR XML PATH('')) , ' ', ',')
FROM tb AS a
GROUP BY id
结果与第三种一样。