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Re: database design method

From: Jan Hidders <hidders_at_REMOVE.THIS.uia.ua.ac.be>
Date: 29 Oct 2002 17:53:41 +0100
Message-ID: <3dbebd15$1@news.uia.ac.be>


Leandro Guimar„es Faria Corsetti Dutra wrote:
>Jan Hidders wrote:
>
>> Leandro Guimar„es Faria Corsetti Dutra wrote:
>>
>>> Jan.Hidders wrote:
>>>
>>>> Sure it has. It can use the same language that you can use for
>>>> the relational model: 1st order logic.
>>>
>>> Now I want to see it. References, please. You may want to be
>>> informed of articles against your view in http://dbdebunk.com./,
>>> for instance.
>>
>> Dbdebunk is not the gospel.
>
> No, but it is a nice reference site and eye-opener.

Sure, but that doesn't mean that everything they say is true. So pointing to an article of theirs and say "and therefore you are wrong" is not a good argument.

>> The fact that you can use FOL to describe constraints in the ER model is
>> so plainly obvious to people who know about logic and ER models that no
>> serious researcher would write an article about that.
>
> What about Fabian Pascal as "serious"? What about
>http://dbdebunk.com./fp4a.htm as an article? Or take Date and
>http://dbdebunk.com/kimball1.htm.

Where exactly in those articles do they claim that you cannot use FOL to describe constraints in the ER model?

>> If you think there is an inherent problem there then I suggest you
>> share it with us and I will be happy to explain why it isn't a
>> problem. :-)
>
> OK. How do you express non-RI constraints? How one does express each
>domain, attribute, relation and database integrity constraints? Or in a
>different taxiology, take transition constraints, how would ERDs represent
>them? I'm not saying you mightn't have a partial answer, but I very much
>doubt you could give (or point to) a complete answer.

All of the above can be done in first-order logic with the obvious limitation that you cannot express what you can express in higer-order logics but not in first-order logic. Again, what do you think is the problem? You do know what first-order logic is, do you? Received on Tue Oct 29 2002 - 10:53:41 CST

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