Re: database systems and organizational intelligence

"x" <x-false_at_yahoo.com> wrote in message news:40b5c7c3_at_post.usenet.com...
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> "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message
> news:c94eft$sfl$1_at_news.netins.net...
> > "Alan" <not.me_at_uhuh.rcn.com> wrote in message
> > news:gvdtc.22728$4%3.3430_at_nwrdny01.gnilink.net...
> > > Top-posting - please don't shoot me.
> > >
> > > The definitions, examples, and explanations I've given of functional
> > > dependency are either quoted directly or paraphrased slightly from
> > > "Fundamentals of Database Systems" 3rd Ed. by Elmasri & Navathe. This
> > text
> > > is used in Masters programs at major universities.
> >
> > I haven't read this book (do you recommend it?), but from this text you
> are
> > able to determine that functional dependencies have nothing to do with
> > functions?
> >
> > > GPA as you have described is an example of "derived" data. It is based
> on
> > > data already stored. Of course code and functions (which are just
> > > pre-written chunks of code)
> >
> > Functions can be specified with code. A function is, by definition, a
> > relation. I wouldn't call any relation, including a function a chunk of
> > code, but there is the specification (formula) for the function, which
is
> > encoded in some way.
>
> I have heard many times that functions are a particular kind of relations.
> But the term function has a nuance of action and the term relation has a
> nuance of stability.

It's an illusion ;-)
The word function is a noun, but it describes a mapping from here (domain) to there (range). Taking it out of mathematics into other uses in English, if an object has a certain function, then it DOES something, which perhaps accounts for your perception of instability. Of course, taking "relations" out of mathematics to English, it has connotations of kin or even bedroom activities. So, I think it is the mathematical definitions that are typically more applicable in this forum.

> > > are needed to extract data, but that does not
> > > mean that code and data are the same thing. You are essentially saying
> > that
> > > driving a car and directions to a destination are the same thing.
> > Directions
> > > are data (information, actually), driving is code (specific actions
> taken
> > to
> > > affect a certain result). They are two different things.
> >
> > In that case, source code is data and object code that is "running" is
> code,
> > right? What about data that is fed as input to code to alter the course
> > (e.g. parameters)? Is it data as coded (source code) and then code when
> > applied during execution or does it remain data throughout? If source
> code
> > is executed by an interpreter instead of a compiler, then does it switch
> > from being instructions (data) to code when the interpreter is taking it
> in
> > as parameters? I don't think you have hit the nail on the head with
this
> > distinction of directions vs. driving, but I could be wrong (it's
happened
> > before).
>
> I'd suggest that code is the driving code not the specific actions.

I don't follow this -- please explain. Thanks. --dawn Received on Thu May 27 2004 - 13:26:36 CEST