Re: Principle of Orthogonal Design

From: David Cressey <>
Date: Tue, 22 Jan 2008 21:36:08 GMT
Message-ID: <cltlj.3537$uB6.1466_at_trndny05>

"JOG" <> wrote in message
> On Jan 22, 7:07 pm, "David Cressey" <> wrote:

> > But "home phone number // work phone number" sure looks like gen-spec
> > me.
> > "phone number" is data that can be applied to a "telephone"
> > a "home phone" is a specialized phone. (Actually, it isn't the
> > but the telephone line or more specifically the associated service
> > that is peculiar to either home or work).
> Keep your dastardly OO away from my query neutral data, and leave it
> in Smalltalk where it belongs ;)
I plead not guilty. ER modeling sometimes has the gen-spec pattern added to the other patterns.

See the U Texas data modeling website.

> Given:
> - Frank's home telephone number is X
> - Franks work telephone number is Y
> - Tom's home telphone number is Z

We don't need "numbers" in the context of this discussion.

What's not clear to me is whether we have any attributes that are unique to home phones or to work phones.

That depends on the U of D. Also, "Frank's work telephone number is Y" might really mean "Frank can be reached, at work, at telephone number Y".

Oops, I forgot. We aren't supposed to be discussing meaning. Received on Tue Jan 22 2008 - 22:36:08 CET

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