Re: Clean Object Class Design -- What is it?
Date: Wed, 18 Jul 2001 00:35:44 -0400
Message-ID: <9u857.95$0j.34509848_at_radon.golden.net>
>>>Object databases take care of
>>>inheritance hierarchies internally.
>>
>> As do relational databases.
>
>I don't understand how a relational database can represent
>inheritance. Most of the time, I can take an object model and
>logically map it to a relational model, because of, well, the
>relationships, but how do you model inheritance in a DB?
That depends. If you are talking about inheritence among the domains of the database, you do it like you would in any other OO language.
If you are talking about sub-type/super-type relationships among relations, I should point out that Fabian Pascal's latest book has an entire chapter devoted to the subject -- an excellent chapter in my opinion. In extremely short form, you model it as a one to zero-or-one relationship between the super-type and the sub-type. Received on Wed Jul 18 2001 - 06:35:44 CEST