Sql Server-- Function

Question

Hi,

I have one table that having 3columns like..

id sub_id name

1 1         mark

I wrote below code to implement function on sub_id column of table that user can see only Sub_id like K00ID1.

create function [bdo].[sub_id](@id int)

return char(12)

as

begin

return 'K00ID'+id

end

I want like this my table.

id sub_id name

1 K00ID1 mark

i tried above function but it is not working... can u help me to sort out this problem