Actually, it sounds like a case of what CJ Date calls the "First Great Blunder", which is equating object classes with tables (as opposed to domains/data types).

Date would probably suggest using three tables (common attributes in one, unique attributes in two others) and views to solve the problem that was originally posted. Unfortunately, no RDBMS today supports proper (always updateable) views, AFAIK.

In reply to Re: Re: SQL Joins across Subclasses by autarch
in thread SQL Joins across Subclasses by djantzen

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