Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]

VC wrote:
> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
> news:5DBze.140518$UG6.7398446_at_phobos.telenet-ops.be...

>>VC wrote:
>>
>>>Let's try another approach.  *When* does one need "conceptual objects" 
>>>and "semantic domains" as opposed to just objects and domains ?  On what 
>>>specific occasions ?  I hope you agree, since you've excised this part of 
>>>my message,  that U.o.E vs. U.o.D contradistinction does not make much 
>>>sense. If you do, the may question stands:  what is a "conceptual object" 
>>>?
>>
>>When you are making a data model there are certain things you want to 
>>describe, and certain things you do not want to describe.

You are right that *in the model* we do not make that distinction. But if we talk *about* the model, and especially when we talk about what should and should not be in it, then of course we do. When modeller 1 asks modeller 2 "Do you think we should describe stacks and linked lists in our model?" then the answer might be "No, I don't think these are conceptual objects here." For them the question about what is and is not described in the model is of course important. That is really all there is to it.

> P.S. I presume a "semantic domain" is composed of "conceptual objects",
> right ?

Yes, actually "semantic domain" and "object type" are the same thing, as far as I can see.

• Jan Hidders