SQL合并字符串

create table ta(a varchar(100),b varchar(100))
insert into ta(a,b) values('a','1')
insert into ta(a,b) values('a','2')
insert into ta(a,b) values('a','3')
insert into ta(a,b) values('b','5')
insert into ta(a,b) values('c','3')
insert into ta(a,b) values('c','2')
insert into ta(a,b) values('c','6')
insert into ta(a,b) values('c','7')

go

create function strhb(@a varchar)
returns varchar(8000)
as
begin
  declare @str varchar(8000)
  set @str = ''
  select @str = @str+',' + b from ta where a = @a
  set @str = right(@str , len(@str)-1)
  return(@str)
End
go

select distinct a,dbo.strhb(a) as b from ta

drop function dbo.strhb
drop table ta