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Re: Polymorphism in RDBMS

From: Ian Pilcher <i.pilcher_at_comcast.net>
Date: Fri, 23 Apr 2004 17:28:54 GMT
Message-ID: <qncic.20622$GR.2834799@attbi_s01>


Alan wrote:
> What you've got there is wrong. If one field or the other must be null, then
> you need the two tables you started with. Polymorphism is an OO concept, and
> is not supported directly in an RDBMS. Why do you think you need to combine
> them?

Sorry I wasn't clear. I don't plan to eliminate the group_info and person_info tables. I do, however, need a way to associate a piece of music with an "artist", regardless of whether the artist is a group or an individual.

I need to "combine" polymorphism and an RDBMS because music can be written/arranged/performed by either "groups" or people. In this case, the real world is very much "polymorphic".

-- 
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Ian Pilcher                                        i.pilcher_at_comcast.net
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Received on Fri Apr 23 2004 - 12:28:54 CDT

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