Cannot Get Values For Using Exec(@query)

hello friends!!
i am getting values from front end application as 1,2

i am using it as '''1'',''2'''

i am writing stored procedure

create proc [dbo].[test_1]
@id varchar(40)
as
begin
declare @str as varchar(500)
select * from table_1 where convert(varchar,uid )in (select @id)
end

and another is

create proc [dbo].[test_1]
@id varchar(40)
as
begin
declare @str as varchar(500)
set @str = 'select * from table_1 where convert(varchar,uid )in ('+@id+')'
exec(@str)
end

my table structure is name : table_1
columns datatype
uid int
uname varchar(10)

why i am getting null values for first stored procedure and if i am using second one i am getting values in query analyser but not in front end i am using ms visual studio 2005 and getting @return_value as 0 but not actual data

is there any link where i find code source for getting data through stored procedure using exec(@querystr)

T.I.A