Re: Database design, Keys and some other things
Date: Tue, 27 Sep 2005 09:32:55 +0300
Message-ID: <dhap2s$7hr$1_at_domitilla.aioe.org>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:1127753335.528946.79940_at_f14g2000cwb.googlegroups.com...
> Ok, to describe that better with an example:
> Consider you have a car and over 20 years you gradually bit by bit
> change every single part of it. The paint job, the engine, the
> interior, the chassis... everything, bit by bit. After 20 years it
> doesn't have a single component that was originally in it. It is still
> the SAME car?
> If yes, then you might agree that the RM model is insufficient and
> breaks down.
I would hope it becomed a better car :-)
> If no, then at what point did it become a different car?
> When the first component changed, when the last component changed, when
> it was 50% changed? There is absolutely no satisfactory answer.
When a car is moved. :-)
> The implication is that to refer to it, every single tuple should have
> an artificial key representing our concept of it.
Our concept is artificial :-)
A car is artificial. :-)
Received on Tue Sep 27 2005 - 08:32:55 CEST