Re: Empty String IS NOT NULL

Good old ternary logic! A statement can have value of "truthiness" (a Colbert report word): that is either true, false or null. The old barber's paradox no longer works with such logic and neither do many of the legendary mathematical theorems which rely on barber's paradox, like the non-existence of set of all sets. Ternary logic is a very twisted thing indeed. I am not sure that Goedel's incompleteness theorem would work in that setting. In a ternary logic system, a proof by contradiction no longer works, so we would lose a good deal of mathematics.

I humbly apologize for this digression but my background (Bsc in mathematics) got the better of me. I remember how surprised I was when I figured out that relational database system is using ternary logic. It was a long, long time ago, in a country far, far away.

On 5/26/20 4:24 PM, Mark W. Farnham wrote:
> In Oracle the empty string is considered to be NULL.
>
> A NULL is not equal to an empty string.
> One NULL is not even equal to another NULL.

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Mladen Gogala
Database Consultant
Tel: (347) 321-1217

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