🚀 go-pugleaf

Hi,

More unexpected SQL behavior.  Here part of a post from another forum
I'm working with,
news://gmnews.goldminesw.com/Public.GoldMine.Programming .  As
background, you need to know that ContSupp has one record with AccountNo
= "90CF-SYSTEM-REC"; the RecType of that record is blank.

Nelson/GM wrote:
> Wierdness.. I tried the following:
> 
> SELECT  * FROM ContSupp WHERE  (Contsupp.AccountNo = '90CF-SYSTEM-REC') and
> (RecType <> 'H')
> 
> And no records were returned. I should have seen one record.  So then I
> tried:
> 
> SELECT  * FROM ContSupp WHERE  (Contsupp.AccountNo = '90CF-SYSTEM-REC') and
> (NOT RecType = 'H')
> 
> And guess what, my one record was returned! Very strange this SQL...  After
> some reading it turns out that SQL has three logic values, TRUE, FALSE or
> NULL. My theory is that for some reason <> returns a NULL condition on an
> unpopulated RecType like that used by the '90CF' record. This is probably
> due to the fact  that <> tests if a value exists (greater than or less than)
> where as the NOT test that a value does not exist.

Are "<>" and "NOT =" really supposed to give different results?  Is
Nelson correct that it has something to do with NULL?

Thanks,

Mark Berry