Martijn Tonies wrote:

>>But the key here is that NULL means unknown (to others than the wallet
>
> Not always, remember the mantra? "null is a state, not a value".

If we call it a state or a value doesn't really matter if you just keep
in mind that NULL means "unknown". I mean, to most of us "the state of
unknown" is pretty much the same thing as "an unknown value". I know
there's a technical difference, but the point of this thread is to gain
an intuitive understanding of how NULL affects expression evaluations in
SQL, and at least to me "state" doesn't help. Thinking "unknown" does.

Kjell
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