[AccessD] An Interesting question

Charlotte Foust cfoust at infostatsystems.com
Mon Mar 30 10:33:14 CDT 2009


No, Drew, Null is NOT a representation of a value, it is a
representation of the absence of a value.  A hole in the ground exists
and has a shape.  A null has no shape because it doesn't exist!

Charlotte Foust 

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Drew Wutka
Sent: Sunday, March 29, 2009 7:00 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] An Interesting question

LOL.  

Sure, I love a good debate...it's been to quiet around here anyways!

You're arguments are based on pure logic, which don't always hold true
when it comes to a computer system.  Ironic, eh?

Case in point, it is logical to assume that 0=0, but in some instances,
0<>0.  It can happen when you use a signed integer, you can end up with
-0.  In that case, even though the numeric value is 0. the sign bit is
turned on, so a computer will see 0<>-0.  Mathematically, there is no
such thing as a -0, but a computer can run into such an occurrence.

Now, null is a value representation just as 5, or 'hello', or 2/10/1999
is a value representation.  5 means nothing other then 5.  In a field of
'NumberOfUnits', then 5 represents the number of units.  Null is a field
value that represents a 'null value', which is a value that has not been
set.  It's a special condition.  An empty string is not null, it's an
empty string.  Null represents a value that has never been set before
(because as far as I know, you can't actually set a field to null once
it has had a value set...).

You're ball...

;)

Drew





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