create table t (ID int, TYPE char(1), NAME varchar(20))
insert t
select 1, 'D', 'SMITH' union all
select 1, 'D', 'DOE' union all
select 1, 'P', 'RICH' union all
select 1, 'P', 'GARMIN' union all
select 2, 'D', 'JEN' union all
select 2, 'D', 'DORTHY'

go
create function dbo.getname(@id int, @delim varchar(5), @type char(1)) 
returns varchar(8000)
as
begin
	declare @out varchar(8000)

	select @out = coalesce(@out + @delim + name, convert(varchar, @id) + ', ' + name)
	from	t
	where	id = @id
	and	type = @type

	return @out
end

go

select	dbo.getname(1, '|', 'D')
select	dbo.getname(2, '|', 'D')

drop function dbo.getname
drop table t


OUTPUT:
------------------------
1, SMITH|DOE

-----------------------
2, JEN|DORTHY