Re: Objects and Relations

On Feb 20, 8:05 pm, "dawn" <dawnwolth..._at_gmail.com> wrote:
> On Feb 16, 9:32 pm, "Marshall" <marshall.spi..._at_gmail.com> wrote:
>
>
>
> > On Feb 16, 4:37 pm, "Keith H Duggar" <dug..._at_alum.mit.edu> wrote:
>
> > > I would like to claim that this very discussion reveals one
> > > of the advantages of trying to think without entities. It
> > > encourages us to think about the /problem/ instead. That is
> > > to think about our goals, our requirements, our knowledge,
> > > etc. It forces us to consider the facts at hand and those
> > > that may arise and design solutions for handling them.
>
> > Yeah.
>
> > I used to have to deal with this vaguely uneasy
> > feeling that terminology was an indicator of some
> > piece of wisdom that I didn't have access to.
> > So I'd hear talk of, say, UML or OOAD or whatever
> > and think, oh, heck, I better learn what that is.
> > So I'd buy a book and it'd be really hard to understand.
> > I'd push and push, and eventually I'd figure out
> > that they were just doing something straightforward,
> > like "programming" or "data modelling" or something,
> > but they had dressed it up in some fancy clothes,
> > added some extraneous concepts, applied some
> > arbitrary rules, etc. The intent was to obscure
> > rather than to reveal. Make it look like more than
> > it was. Really annoying.
>
> > I remember reading a guy on comp.lang.functional
> > describing going through the same process, but
> > over the phrase "dependency injection." After a
> > week of reading he figured out it meant "abstraction"
> > (as in "lambda abstraction.") In other words it was
> > just the process of parameterizing code.
>
> > The thing about entities is, what does it buy me?
> > I've got relations; I know how they work. Now I'm
> > supposed to layer this "entities" concept over the
> > top of that. What do I have now that I didn't before?
>
> > Seriously, what?
>
> > Marshall
>
> I use entities in conceptual modeling. I do not see a need for it in
> logical modeling, although it is just a level of abstraction away and
> some products (or standards such as XML) use the term in the logical
> layer as well. Relations do not fall from the sky, so how did you
> know what relations to design?

Ah yes, but propositions do fall from the sky.

> You likely looked at nouns/entities/
> things at some point, with "entities" being the preferred term (as
> best I can tell).
>
> I'm in the middle of writing up tips for going from entites and their
> properties to relations and attributes when working with a non-1NF 2VL
> DBMS, since there is already plenty written on this in the case that
> the target DBMS is an SQL-DBMS. If anyone knows of anything written
> on this subject (the one I'm writing on), please pass along any
> relevant URLs. I have been highly unsuccessful in finding other write-
> ups on this.
> Thanks --dawn
Received on Tue Feb 20 2007 - 23:05:50 CET