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 [EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]