Re: Database-valued attributes?

From: Alfredo Novoa <alfredo_at_ncs.es>
Date: 11 Nov 2003 03:57:00 -0800
Message-ID: <e4330f45.0311110357.29213295@posting.google.com>

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:<_C_rb.122225$9E1.607217_at_attbi_s52>...

> what about
> database-valued attributes? That is to say, what about an attribute
> that consists of a set of relation values?

It is simply RVAs with RVAs.

If you want relations containing relations of diferent types you could define a type called RelationType that would be the set of all relation values.

var a base relation { b RelationType } key { b };

a := relation { tuple { b relation { a integer, b integer }

                                   { tuple { a 1, b 2 }, 
                                     tuple { a 1, b 3 } } },
                tuple { b relation { tuple { t 'Hello' },
                                     tuple { t 'Marshall' } } } };

Regards
Alfredo Received on Tue Nov 11 2003 - 05:57:00 CST