Re: The BOOLEAN data type

Just because an operation exists for a type doesn't mean it has to make sense for every entity represented by that type. What does the concatenation operator mean for City?

True did not become male or female any more than 17 became an age (never again to be an integer) when someone used an integer for an age in a schema. The observation that a dog is a mammal does not make mammals into dogs.

As for implication, even though there is no requirement that it make sense for every boolean entity, one might want to test the theory that an child born within 30 seconds of a Male is not a Male:

not exists (
select * from Children C1, Children C2
where C2.Birth between C1.Birth and dateadd(second,30,C1.Birth) and not (C1.HasYChromosome --> not C2.HasYChromosome) )

SK

Bob Badour wrote:

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>>However, the children's maleness or femaleness is boolean!
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>If that is the case, please explain what the implication operation means for
>gender. When and how did true become male or female?
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Received on Thu Apr 10 2003 - 09:07:41 CEST