Sql Function for String Concatenation

create function dbo.test2(@l3code varchar(20))
RETURNS varchar(2000)
As
BEGIN
Declare @var varchar(2000)
set @var=''
Select @var = @var +'#'+ keyword from keyword where level3code=@l3code
group by level3code,keyword
return @var
END
select distinct level3code,dbo.test2(level3code) from keyword