Re: By The Dawn's Normal Light

"Dawn M. Wolthuis" <dwolt_at_tincat-group.comREMOVE> wrote in message news:cle65t$m52$1_at_news.netins.net...

> I'm definitely a fan of ERDs. In fact, in trying to teach OOAD right now
> with UML 2.0 diagrams, I had to figure out how to handle my two favorite
> tools -- DFDs and ERDs. Class diagrams really did work quite well for
ERDs,
> with the relationships on lines instead of triangles, for example.

You might want to look at Object Oriented Analysis by Coad/Yourden, or something similar but more up to date.

I found that knowing what I did about ERD made it possible for me to get a lot out of OOA, in psite of not having any kind of strong background in OOP.

Funny you should mention DFDs. That's also another of my favorite tools.

> > The good news is that converting an ER model into an SQL model is so
> > straightforward that an engine like DA can do it automatically. And
even
> if
> > you don't have a tool like DA, it's still a simple exercise.
>
> And that is where we differ. Yes, we can discuss the business with uses
and
> an ERD up until the point where we want to show them how to get their
> information back out of the system. With systems that have more than,
say,
> 400 tables, I have never seen a satisfactory implementation of a set of
> views that satisfies the users with both data and performance. It makes
> them think differently than the ERD does.

I think there may be a problem here, indeed. It's been my experience that SQL does NOT turn data back into information, no matter how clever you are. A result table is still data, even if it's a lot more relevant than it was in the DB.

I think other tools are needed to feed users. Report writers, OLAP tools, who knows?

Most of the time, I'm concerned about feeding the data to other apps rather than to people. And SQL is adequate (although far from perfect) in that regard. Received on Sat Oct 23 2004 - 20:26:26 CEST