Re: domain questionnaire

In article <96n31l$1uf$1_at_news.tue.nl>, Jan Hidders says...

>> 2. weight in lbs vs. weight in kgs
>
>The crucial question is again how you are going to denote them. Are you
>going to write one kilogram as '1 kg' or just '1'. In the first case
>you can have 1 ADT describing them both, in the second case you need
>two.
>
Then, definition of domain becomes dependent on the relation that uses it. This doesn't look like traditional interpretation of what domain is... Or this denotational idea is an additional element that we need to bring into relational theory?

>> 3. US voice stationary phone numbers vs. fax numbers vs. cell numbers
>
>This is a subtle one. Date allows subdomains (or subtypes, or
>subclasses, or whatever you wanna call them :-)). So, in some sense
>these all belong to the domain 'phone number' but are in the same time
>different subdomains. But these are not really good domains because
>domains should be static, or, to be more precise, just as dynamic as
>the rest of the database schema. And since phone numbers can change
>their role quite fast, this should not be modeled with (sub)domains.

If unified phone domain is a good thing, shouldn't I squeeze email addresses into this domain as well? Where do I stop in my generalization effort? Received on Mon Feb 19 2001 - 23:33:43 CET