Path: newssvr20.news.prodigy.com!newsmst01.news.prodigy.com!prodigy.com!rip!news.webusenet.com!feed2.newsreader.com!newsreader.com!newshosting.com!news-xfer1.atl.newshosting.com!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.cs.utexas.edu!geraldo.cc.utexas.edu!an02.austin.ibm.com!ausnews.austin.ibm.com!newsfeed.btv.ibm.com!gazette.almaden.ibm.com!not-for-mail
From: "Paul Vernon" <paul.vernon@ukk.ibmm.comm>
Newsgroups: comp.databases.theory
Subject: Re: Database-valued attributes?
Date: Tue, 11 Nov 2003 18:50:39 -0000
Organization: IBM Almaden Research Center
Lines: 60
Message-ID: <borb84$127k$1@gazette.almaden.ibm.com>
References: <_C_rb.122225$9E1.607217@attbi_s52> <boqjj0$18lk$1@gazette.almaden.ibm.com> <fX7sb.174252$e01.608500@attbi_s02>
NNTP-Posting-Host: dyn-9-140-177-27.warwick.uk.ibm.com
X-Trace: gazette.almaden.ibm.com 1068576836 35060 9.140.177.27 (11 Nov 2003 18:53:56 GMT)
X-Complaints-To: postmaster@almaden.ibm.com
NNTP-Posting-Date: Tue, 11 Nov 2003 18:53:56 +0000 (UTC)
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2800.1158
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165
Xref: newssvr20.news.prodigy.com comp.databases.theory:22631

"Marshall Spight" <mspight@dnai.com> wrote in message
news:fX7sb.174252$e01.608500@attbi_s02...
> "Paul Vernon" <paul.vernon@ukk.ibmm.comm> wrote in message
news:boqjj0$18lk$1@gazette.almaden.ibm.com...
> >
> > Just need to agree on what a database value actually is.  If it is a
'set of
> > relations' what happens if two relations contain the same set of tuples
(of
> > the same type), but have different 'relation names'? Are they different
> > relations?
>
> Well, if you have two "top level" relvars in a database with exactly
> the same contents but different names, is that any problem?  I'm not
> aware of any problems.

Principle of Orthogonal Design. But lets not go there.

> I would say "yes, they are different relations."

You mean "different relvars containing the same relation values"

> Consider: we create a relation var "Primes" for interesting prime numbers
> we've calculated, and a relvar "Perfect" for interesting perfect numbers
> we have calculated. We're just about to run the applications that will be
> filling these relvars, so they're both currently empty. So they have
> the same set of tuples of the same type, but are different relvars.

What is to consider?
I'd just use two tuple types. E.g.

    { <Prime:Integer> }
and
    { <Perfect_Prime:Integer> }


> > If so does that mean that if *relation variables* have names,
> > then *relation values* must also have names? I.e. I suggest that either
> > neither relation values and relation variables have names, or that both
do.
> > I suggest we cannot have either-or.
> >
> > :-)
>
> I guess I'm not following you. Maybe the smiley means you're being
> funny? But I don't get the humour.

No, my smiley was because I could say *a lot* more than I did above.

> Perhaps I'm just in overly-literal mode today.

Never a bad mode to be in. Perhaps you could ponder on this one. If a
database contains relation *variables* does that mean that a Database Valued
Atrribute also contains variables?

Regards
Paul Vernon
Business Intelligence, IBM Global Services