Ah, you cite David Hay. He's the best! His new book, Requirements = Analysis from Business Views to Architecture is excellent!! He shared = one of his themes, "Making Your Entities Behave: Entity Life Histories" = in the ODTUG Technical Journal (December, 2002). It's one of his best = and on the ODTUG web site at www.odtug.com. I hope to hear some of his = presentations at the ODTUG conference in June. As an academic exercise, I recall one developer who modeled the = universe with two entities, "things" and "thing types". After some = discussion, we realized that "thing types" were actually "things" also. = Hence, we were down to one entity. Of course it had a recursive = relationship. And yes, there would be a lot of code to write to make it = work. :-) Respectfully, > Maggie Tompkins - CAD SQA > Corporate Applications Division > Technology Services Organization - Kansas City > Defense Finance and Accounting Service > 816-926-1117 (DSN 465); Margaret.Tompkins@xxxxxxxx -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Jared Still Sent: Sunday, February 08, 2004 11:25 AM To: Oracle-L Freelists Subject: RE: Academic ERDs vs. Professional ERDs But of course, there is after all only one data model required; http://www.tdan.com/i005fe03.htm Everything else is fluff. Jared On Sat, 2004-02-07 at 20:16, TOMPKINS, MARGARET wrote: > Just a guess but some of that may have come out of mathematical set = =3D > theory, sometimes called relational set theory. That at least dates = =3D > back to Venn diagrams. > I have worked with groups that do nothing but data modeling either = in =3D > tools like Designer or ERWin. They don't model to define requirements = =3D > to be implemented. They data model - period. The biggest difference = =3D > that I've seen in those and the "real" ones is an overuse of entity = =3D > subtyping. Entities that have eight levels of subtyping are beyond my = =3D > comprehension. Maybe it's good that they don't get implemented. = Maggie >=20 > Respectfully, > > Maggie Tompkins - CAD SQA > > Corporate Applications Division > > Technology Services Organization - Kansas City > > Defense Finance and Accounting Service > > 816-926-1117 (DSN 465); Margaret.Tompkins@xxxxxxxx >=20 >=20 > -----Original Message----- > From: oracle-l-bounce@xxxxxxxxxxxxx > [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Ryan > Sent: Saturday, February 07, 2004 3:14 PM > To: oracle-l@xxxxxxxxxxxxx > Subject: Re: Academic ERDs vs. Professional ERDs >=20 >=20 > They are very similiar to class diagrams which are used outside of =3D > academia. > ----- Original Message ----- > From: "Tim Gorman" <tim@xxxxxxxxxxxxx> > To: <oracle-l@xxxxxxxxxxxxx> > Sent: Saturday, February 07, 2004 2:55 PM > Subject: Re: Academic ERDs vs. Professional ERDs >=20 >=20 > > If it is not used outside of academia, then it is either ahead of = its =3D > time > > (due for general adoption) or of absolutely no practical use =3D > whatsoever. > > > > Given that decision-tree, how long have these concepts been around? = =3D > I'm > > sure the footnotes have dates... :-) > > > > > > > > > > on 2/7/04 9:47 AM, Ryan at ryan.gaffuri@xxxxxxx wrote: > > > > > I'm taking academic database classes and last semester we covered > academic > > > ERDs. The material in the book discussed 'entity sets' and =3D > relationship > sets. > > > The relations between them seemed very similiar to relations in a = =3D > class > > > diagram. > > > However, I when I look into Erwin and Designer the ERDs there seem = =3D > to be > > > closer to table models. Does anyone use the academic type of ERDs > > > professionally? > > > > > > ---------------------------------------------------------------- > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > > ---------------------------------------------------------------- > > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > > put 'unsubscribe' in the subject line. > > > -- > > > Archives are at //www.freelists.org/archives/oracle-l/ > > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > > ----------------------------------------------------------------- > > > > ---------------------------------------------------------------- > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > ---------------------------------------------------------------- > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > put 'unsubscribe' in the subject line. > > -- > > Archives are at //www.freelists.org/archives/oracle-l/ > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > ----------------------------------------------------------------- > > >=20 > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > put 'unsubscribe' in the subject line. > -- > Archives are at //www.freelists.org/archives/oracle-l/ > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > put 'unsubscribe' in the subject line. > -- > Archives are at //www.freelists.org/archives/oracle-l/ > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------