Are there any rules of thumb on when to use one over the other? I have a page item P2_STUDENT_ID, that can either get set from another page using a URL redirect or needs to get a default value from SQL if not coming from that page and is null in session state.
Is it better to use a computation for the page item or the page item's source to set this default value? What are the pros and cons of each, or is it just a matter of preference?