Re: Extending my question. Was: The relational model and relational

"Bernard Peek" <bap_at_shrdlu.com> wrote in message news:ixbyZQwB3AW+EwXz_at_diamond9.demon.co.uk...
> In message <7Ik5a.164$8e.17186852_at_mantis.golden.net>, Bob Badour
> <bbadour_at_golden.net> writes
>
>
> >It's interesting how you are trying to mischaracterize Date as using
> >primitive technology. Multisets are demonstrably more primitive than
> >relations--simply from the fact that they rely on physical location. You
are
> >the one promoting the use of "Roman numerals and shells".
>
> Multisets may rely on physical location, although that's a special case.

That's a very remarkable statement. By what other means may users of a dbms using a multiset logical data model make use of duplicates?

> The general case is that they rely on information outside the database
> to distinguish different items.

Really? That's quite extraordinary. How does the dbms use this external information in its logical data model?

> If that happens to be physical location
> then you can add the current latitude, longitude and altitude as a key.

Are you being facetious?

> There are some practical problems but in theory it's possible. In
> practise if you need to distinguish two cans of tuna you create an
> identity field, call it "Can Number" and print labels to stick on each
> can.

I've identified plenty of cans on shelves, but I've never seen a "Can Number". Where might I find one of those? Received on Sun Feb 23 2003 - 04:25:22 CET