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')
go
-- 方法一：
-- 1. 创建Function
create function dbo.f_str(@id varchar(10)) returns varchar(1000)
as
begin
declare @str varchar(1000)
select @str = isnull(@str + ',' , '') + cast(value as varchar) from tb where id = @id
return @str
end
go
-- 2. 调用Function
select id , value = dbo.f_str(id) from tb group by id
drop function dbo.f_str
-- 方法二：
select id, [value] = stuff((select ',' + [value]
from tb t where id = tb.id
for xml path('')) , 1 , 1 , '')
from tb
group by id
drop table tb