Re: RA with MV attributes

From: JOG <jog_at_cs.nott.ac.uk>
Date: 17 Jan 2007 17:42:13 -0800
Message-ID: <1169084533.424030.204440@11g2000cwr.googlegroups.com>

David wrote:
> Marshall wrote:
> > David wrote:
> [snip]
> > > 2. It deals rather elegantly with missing information.
> >
> > I don't get this point either.
>
> Subject to integrity constraints, a tuple can map an attribute to an
> empty set.

The more I think about this the less it makes sense to me. Which representation is the most elegant?

Bill does not have a car.
Bill has an {} car.
Bill has a NULL car.

I'll take number one. Received on Wed Jan 17 2007 - 19:42:13 CST