Re: 3vl 2vl and NULL
From: JOG <jog_at_cs.nott.ac.uk>
Date: 6 Dec 2005 06:11:26 -0800
Message-ID: <1133878286.862752.99140_at_g49g2000cwa.googlegroups.com>
Date: 6 Dec 2005 06:11:26 -0800
Message-ID: <1133878286.862752.99140_at_g49g2000cwa.googlegroups.com>
michael_at_preece.net wrote:
> What type of liquid is stored in an empty mug? Is it "unknown"? No - it
> is not an unknown type of liquid. It is no liquid. The value of the
> "liquid" column for the row would be empty. It would be NULL.
>
> Super,
> Mike.
Oh lordy. It never ends. An empty mug contains no liquid. It hence HAS NO liquid column. Trying to fit it in a table WITH a liquid column is therefore impossible - it violates the predicate logic the system is based on. That is all there is to it. Received on Tue Dec 06 2005 - 15:11:26 CET