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

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

--调用函数

select id , value = dbo.f_str(id) from tb group by id

drop function dbo.f_str

drop table tb
 

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

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

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

declare @t table(id int,value varchar(100))--定义结果集表变量

--定义游标并进行合并处理

declare my_cursor cursor local for

select id , value from tb

declare @id_old int , @id int , @value varchar(10) , @s varchar(100)

open my_cursor

fetch my_cursor into @id , @value

select @id_old = @id , @s=''

while @@FETCH_STATUS = 0

begin

    if @id = @id_old

       select @s = @s + ',' + cast(@value as varchar)

    else

      begin

        insert @t values(@id_old , stuff(@s,1,1,''))

        select @s = ',' + cast(@value as varchar) , @id_old = @id

      end

    fetch my_cursor into @id , @value

END

insert @t values(@id_old , stuff(@s,1,1,''))

close my_cursor

deallocate my_cursor

select * from @t

drop table tb