Re: How to prevent updates on foreign key default values

If you want to allow "school not in list" as a possibility, just let student.schoolid be NULL in that case.

Steve Kass
Drew University

"Harlan Messinger" <zzzhmessinger_at_erols.com> wrote in message news:9q1mmp$19$1_at_bob.news.rcn.net...
>
> <MSherrill_at_compuserve.com> wrote in message
> news:3bc3da86.56994633_at_news.compuserve.com...
> > On 07 Oct 2001 17:46:32 +0200, Christoffer Vig <chrde_at_online.no>
> > wrote:
> > >Now what happens if the first thing I do in this database is
> > >register a new student? ( ie. no school has yet been registered)
> >
> > Register a new student for what? In the absence of a school, that
> > doesn't make sense to me. A student without a school isn't a student.
>
> He is a student if "without a school" means "the school hasn't been
entered
> in the database *yet*". Imagine you're a data entry clerk at a large
> foundation that provides research grants to graduate students. You're
> entering one student's application and find that his school isn't listed
in
> the drop-down list/combo box from which you are supposed to select the
> student's school. You're not the person responsible for entering schools
> into the system. Assuming that systems are supposed to reflect the uses to
> which they are put, rather than use cases being rearranged to suit pure
> computational theory, it would seem that the data entry application would
> have to provide a way to indicate "school not in list" for this student.
> Certainly it will be someone else's job to scan the data periodically for
> schools that need to be newly entered, and update the records for those
> students after that has happened.
>
>
>
Received on Wed Oct 10 2001 - 16:47:10 CEST