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

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.