Re: 3 value logic. Why is SQL so special?
From: Gene Wirchenko <genew_at_ocis.net>
Date: Mon, 18 Sep 2006 09:15:28 -0700
Message-ID: <h3htg2hlprsaaefku7gpfakp6cgtqlp13n_at_4ax.com>
Date: Mon, 18 Sep 2006 09:15:28 -0700
Message-ID: <h3htg2hlprsaaefku7gpfakp6cgtqlp13n_at_4ax.com>
Volker Hetzer <firstname.lastname_at_ieee.org> wrote:
[snip]
>What I don't understand is that everyone who decries nulls, somewhere
>works with default values. Ok, big deal, NULL is an universally applicable
>default value that cannot be confused with real data.
>What am I missing?
That it can be confused with real data. For one thing, NULL is *NOT* a value. It is the absence of a value.
>Btw, what would be the consequences of NULL=NULL being true?
The value is unknown. What are the chances of two unknown pieces of data being equal?
Sincerely,
Gene Wirchenko
Computerese Irregular Verb Conjugation:
I have preferences. You have biases. He/She has prejudices.Received on Mon Sep 18 2006 - 18:15:28 CEST