Thanks Matthew, (01)
You've written a large number of papers on modeling - my congratulations for
being so prolific. Your papers seem to begin with the concept of data
modeling and then go into the proper principles for modeling. (02)
But I'm looking for ways to use existing database tables and to discover the
classes and relationships that, by chance, went into the original table
design. In my experience, commercial databases are developed in a haphazard
way for nearly all commercial applications without the luxury of careful
modeling. That's especially true of the applications developed as
requirements are being discovered and changes are requested by users that
may not meet the best practices of modelers. Database designers are usually
upset to see the way the databases turn out when created in this de facto
way instead of in a well designed, carefully orchestrated way. (03)
So if you must begin with an existing database's table designs, how can a
reasonable class model be developed for that legacy database? Are there
automatic methods for generating the As-Is class models? (04)
Suggestions, URLs, replies appreciated. (05)
Thanks,
-Rich (06)
Sincerely,
Rich Cooper
EnglishLogicKernel.com
Rich AT EnglishLogicKernel DOT com (07)
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Matthew West
Sent: Saturday, January 31, 2009 1:34 AM
To: edbark@xxxxxxxx; '[ontolog-forum] '
Subject: Re: [ontolog-forum] Is there something I missed? (08)
Dear Rich (09)
>
> > I have always considered the definition of an RDB-class
> correspondence to be
> > partially in the mind of the modeler, not in the RDB structure
> itself. I
> > know of no formal definition of what a RDB-class consists of, which
> would
> > provide a rigorous foundation for translating RDBs to classes with
> one
> > exception; there is at least one class per table. Modelers may often
> add
> > definitions of subclasses within a table, but that's usually some
> form of
> > correspondence between groups of columns from a table that fit within
> the
> > human "chunk" size of 7+/-2 concepts. So it seems every bit as
> subjective
> > as any other method of constructing classes from data. Data mining
> (and
> > text mining) consists of discovering those subclasses, along with
> classes
> > that relate one table to other(s).
>
> I would not dispute any of this.
>
> > Do you have reference(s) (URLs especially) to other documented points
> of
> > view which might more rigorously define how the RDB translates into
> classes? (010)
[MW] I did some work that effectively does this about 15 years ago, which is
captured in a document called "Developing high Quality Data Models". Part of
it is about finding the hidden classes, and part of it is about not hiding
them in the first place. You can find it here:
http://www.matthew-west.org.uk/Publications.html (011)
or just type "High Quality Data Models" into Google. (012)
Regards (013)
Matthew West
Information Junction
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.matthew-west.org.uk/ (014)
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