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

In the article <321B7C7E.41C67EA6_at_unm.edu>, Guy Bassan <gbassan_at_unm.edu> wrote :
> 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)

Well..Yes..and No
NULL is per definition undefined !
Comparing NULL to anything is therfore meaningless even if (NULL=1) = NULL and NOT(NULL=1) = NULL.
A comparison with NULL will always return NULL ! That's why we have the IS NULL consept.

:)

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