Re: Distributed foreign keys (was Re: Category Types)
From: Alfredo Novoa <alfredo_at_ncs.es>
Date: 26 Jun 2003 08:06:42 -0700
Message-ID: <e4330f45.0306260706.4e46ad81_at_posting.google.com>
Date: 26 Jun 2003 08:06:42 -0700
Message-ID: <e4330f45.0306260706.4e46ad81_at_posting.google.com>
"Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message news:<bdck49$19vk$1_at_gazette.almaden.ibm.com>...
> > var a real relation { a integer, b integer };
> > constraint count(a) = count(a{a});
>
> It might be equivalent, but is cardinality the best primitive form? Why not
The form is not important.
> use FDs.
> E.g.
>
> var a real relation { a integer, b integer };
> constraint a -> b
Well, it was not in my list of relational operators :-)
But you forgot the relvar name.
Regards
Alfredo
Received on Thu Jun 26 2003 - 17:06:42 CEST