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Re: What is that "more" that makes E-R model truly independent ?

From: paul c <toledobythesea_at_oohay.ac>
Date: Wed, 25 Jul 2007 16:43:13 GMT
Message-ID: <B4Lpi.6049$rX4.4385_at_pd7urf2no> 






David Cressey wrote:


> "beginner16" <kaja_love160_at_yahoo.com> wrote in message


> news:1185291874.325737.75510_at_w3g2000hsg.googlegroups.com...

...

>>2)
>>Quote from my book:
>>"With conceptual model we can't ( ussually ) define semantics of
>>data".
>>
>>I know what the term semantics means, but not in this context. Does it
>>mean that at conceptual level the diagrams don't tell us the meaning
>>of that data? Uh, that doesn't make much sense
>>




> 

> For what it's worth, it doesn't make much sense to me, either.  The


> concpetual level is precisely where the semantics of the data should be

> pinned down.  Down at the logical level or below, the data is increasingly

> being stored, structured, retrieved and manipulated in ways that are

> independent of what the data really means.  This is where math is helpful.

> 




This reminds me of a quote from another book, "Logic" by  Wilfrid 
Hodges, which Hugh Darwen has mentioned from time to time:



"The task we now approach is that of *formalizing* logic.  To formalize 
is to strip away the concepts which give meaning and application to the
subject, so that nothing remains but bare symbols.  Translation will
disappear first, situations will fade away next, and finally even truth 
will make its exit."



I think this means that a dbms is a logic machine.  When the machine 
gives us its answer to a question, consisting of "nothing but symbols", 
can we then look to a conceptual model to tell us what meaning to take 
from the answer?  If so, does it happen much in practice?



p
Received on Wed Jul 25 2007 - 18:43:13 CEST












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