Sony and Gary,
Null is a "special" condition of data. A data point cannot equal or not
equal null, therefore 'like' and 'not like' also does not work as neither is
true. Therefore SQL recognizes 'null' and 'not null' for the purpose of
evaluating nulls. Consider the null state as being the complete non existence
of the data point only. That being said, then a null neither exists nor does not
exist. It's just NULL.
An instructor put the logic of Nulls this way: In logic things are either
TRUE, FALSE, or NULL.
Dick Goulet
____________________Reply Separator____________________
Author: Sony kristanto <[EMAIL PROTECTED]>
Date: 1/30/2003 6:22 PM
Hi Gary,
I wonder why you didn't use :
select * from tester2 where whatever is null;
Null values is extremely empty.
Rgrds,
Sony
> -----Original Message-----
> From: Gary Jackson [SMTP:[EMAIL PROTECTED]]
> Sent: Friday, January 31, 2003 12:42 AM
> To: Multiple recipients of list ORACLE-L
> Subject: comparing null values
>
> Can anyone explain why it is that I seem unable to use 'like' and 'not
> like'
> on columns containing null values. (I am unable to find information
> regarding this on MetaLink.)
>
> For example:
>
> SQL> select * from tester2;
>
> COL1 COL2 WHATEVER
> ---- ---- --------
> 1 1 STUFF
> 2 2 STUFF
> 3 3
> 4 4
>
> SQL> select * from tester2 where whatever not like '%STU%';
> no rows selected
>
>
> My question is why does this not return the 3 & 4 columns?
>
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