合并同列多行数据为一字符串的最简单方法

相同条件 多行变一行，不知道是不是你要的
declare @tb table (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')

select id , [ccname]=
stuff((select ' '+[value] from @tb t where id =tv.id for xml path('')), 1, 1, '')
from @tb as tv
group by id
/*
id    ccname
1    aa bb
2    aaa bbb ccc*/