Re: Clean Object Class Design -- What is it?

In article <tqt17.30637$3O.5592_at_newsfeed.slurp.net>, Rico says...

>Re: object databases ... not true. As I'm sure has been pointed out to you,
>the relational model simply manipulates sets of tuples using set theoretic
>operations. There is no concept in the model of "inheritence" ... a key
>property of the object-oriented model ... this must be simulated by
>flattening the hierarchy. However, this means that related child objects
>are now in separate relations, and cannot be easily manipulated without
>multiple SQL statements. For example, change the model year of all vehicles
>on the lot at dealership A, where the parent object class Vehicle has been
>subclassed into Sedan, Coupe, and SUV.
>

Only object proponents would irresponsibly partition Vehicles into 3 different tables. In fact is there any significance in assigning 3 separate subclsses to them? You are not going to suggest overriding "drive" method based upon object subtype to dilership owner, arent you? Those vehicles categories are no more than categories that can be just sitting in a single category column. BTW, this column is functionally dependent upon such things as weight, number of doors, fuel efficiency, etc. Received on Sun Jul 22 2001 - 01:34:09 CEST