Re: NULL with IN-Clause

I'm going to quibble.

A NULL is a marker for the absence of a value. The interpretation that the absence of a value implies a value that is unknown is an inference that may or may not have been
implicit in the intent of the process that did not provide a value. I realize this view is not
universally held, but I claim it to be correct.

Having said that, the rest of your remarks are valid and useful, particularly
the distinct behaviour of NULL when tested for equality with itself.

Holmes: We have yet to explain the unusual behaviour of the dog in the night.

Watson: The dog did nothing in the night.

Holmes: That was the unusual behaviour.

-----Original Message-----
From: James Lorenzen <james_lorenzen_at_allianzlife.com> Newsgroups: comp.databases.theory,comp.databases.oracle.misc Date: Tuesday, May 11, 1999 9:11 AM
Subject: Re: NULL with IN-Clause

>Philip :
> A NULL is an unknown value. That means a NULL is never equal to
>anything, not even another NULL. It also means that a NULL is never not
>equal to anything. IE NULL = NULL evaluates to FALSE, therefore the IN
>clause with a NULL in the value list will never return a NULL value.
>
Received on Fri May 14 1999 - 08:42:59 CDT