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

From: Guy Bassan <gbassan_at_unm.edu>
Date: 1996/08/21
Message-ID: <321B7C7E.41C67EA6_at_unm.edu>#1/1

According to Oracle's documentation (which is occasionally correct), whenever you use NULL in any kind of function, you almost always get NULL back. (NULL = 1) is a function that returns a boolean: TRUE, FALSE or NULL. Usually booleans only have two values, but Oracle isn't constrained by silly conventions like that.

Now, since (NULL = 1) is sort of like a function using NULL, the boolean value returned is NULL. Similarly, when you take not(NULL), you are again using a function on NULL, and NULL is again returned. Thus, both times you are doing IF (NULL), and since NULL is not TRUE, the program runs the ELSE condition both times.

To summarize: Yes, (NULL = 1) is equal to NOT(NULL = 1)

Guy Bassan
Los Alamos National Laboratories

Received on Wed Aug 21 1996 - 00:00:00 CEST

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