Re: IS (NULL = 1) equal to NOT(NULL = 1)?

OK You asked for it...
NULL is undefined. NULL might = 1 but can't be determined to be NULL might not = 1 but also can't be determined to be.

So ( NULL = 1 ) = maybe, can't be sure
and NOT( NULL = 1 ) = maybe, can't be sure

since "maybe, can't be sure" = "maybe, can't be sure" then (NULL=1) = NOT(NULL=1)

hope it helps
Randy :)

John Dennis (jtdennis_at_atl.mindspring.com) wrote:

: Of course not right? Oracle says it is!
 

: I have the following *simple* code:
 

: set serveroutput on
: BEGIN
: DECLARE
 
: N NUMBER;
 
: BEGIN
 
: N := NULL;
 
: IF (N = 1)
: THEN
: dbms_output.put_line('TRUE');
: ELSE
: dbms_output.put_line('FALSE');
: END IF;
 
: /* Notice the expression has been "notted" */
 

: IF NOT(N = 1)
: THEN
: dbms_output.put_line('TRUE');
: ELSE
: dbms_output.put_line('FALSE');
: END IF;
 
: END;
: END;
: /
 

: This code returns:
 

: FALSE
: FALSE
 
: Now I've been doing this for a while. I know that 1 is not equal to
: NULL. I thought this meant (1 = NULL) = FALSE which might be true.
: However if it is true then certainly NOT(1 = NULL) would then be TRUE.
: NOT of *any* expression is the opposite boolean value. But not here.
 

: Anyway, if anyone could point out my error here please do so. I
: wouldn't even mind a little "... any rookie that knows anything know
: should know that null, etc..." stuff. Hmmm, well maybe not.
 

: Virtually,
 

: John Dennis

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