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From:abrea Date:July 7 2005 5:57pm
Subject:Re: Another generalization hierarchy problem
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Dear Shawn,
Thanks for your reply.
I find that "individuals" and "companies" each have attributes that 
are completely irrelevant to the other. E.g. "individuals" have sex 
and language (so e-mail can be sent to them as "Dear Sir" or "Dear 
Madam" in both English and Spanish). The only time they have 
information in common is when they are customers, where they have a 
tax id, billing address, sales, etc.

By "company" I mean any juridical entity (I didn't use the 
word "entity" in order not to confuse it with ERD entities). So 
a "company" can have many "individuals" and an individual can also 
have multiple "companies" (e.g. the firm he works for, a club, a 
professional association).

An "individual" can be of the subtype "personal_relation" 
or "customer" but for some persons both types overlap (e.g. a 
personal friend with whom I also do business).

I think that I cannot put 'customer' as the supertype because 
many 'individuals' and 'companies' are not customers (I wish they 
were :-)) so they wouldn't share the 'customer' attributes.

ATTEMPT: I thought of having an "individual_customer" and 
an "company_customer" as subtypes of "individual" and "company", 
respectively.
But in your experience, wouldn't it be a mess to have half of the 
customers in one entity and half in the other?

Best regards,
Alberto Brea
estudio_brea@stripped

Thread
Another generalization hierarchy problemabrea7 Jul
Re: Another generalization hierarchy problemSGreen7 Jul
Re: Another generalization hierarchy problemabrea7 Jul
Re: Another generalization hierarchy problemabrea7 Jul
Re: Another generalization hierarchy problemSGreen7 Jul
Re: Another generalization hierarchy problemPeter Brawley7 Jul
Re: Another generalization hierarchy problemabrea7 Jul
Re: Another generalization hierarchy problemabrea7 Jul