Re: 3 value logic. Why is SQL so special?

From: Roy Hann <specially_at_processed.almost.meat>
Date: Mon, 18 Sep 2006 20:32:35 +0100
Message-ID: <HaudnZ5V94X7aZPYRVnygg_at_pipex.net>

"Gene Wirchenko" <genew_at_ocis.net> wrote in message news:h3htg2hlprsaaefku7gpfakp6cgtqlp13n_at_4ax.com...

>>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?

It's worse than that. Suppose one user can't be bothered to find out if the customer is insolvent and another user decides the null means insolvency or otherwise isn't a relevant attribute.

Roy Received on Mon Sep 18 2006 - 21:32:35 CEST

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