At 09:42 AM 11-08-01 -0600, you wrote:

>Kind of handy
>
>Like extra pizza topping: Null, 'Bacon', 'Cheese'
>
>Null = No extra topping. Subsequently taking advantage
>of the 'no exist' behavour of the Null value.

Ach! here we go again. A not null topping is bacon or cheese. A null topping is "unknown", i.e. it could be rat's brains or chocolate anchovies.

One does not logically select "unknown".

H.

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