RE: Academic ERDs vs. Professional ERDs
- From: "TOMPKINS, MARGARET" <MARGARET.TOMPKINS@xxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 7 Feb 2004 22:16:57 -0600
Just a guess but some of that may have come out of mathematical set =
theory, sometimes called relational set theory. That at least dates =
back to Venn diagrams.
I have worked with groups that do nothing but data modeling either in =
tools like Designer or ERWin. They don't model to define requirements =
to be implemented. They data model - period. The biggest difference =
that I've seen in those and the "real" ones is an overuse of entity =
subtyping. Entities that have eight levels of subtyping are beyond my =
comprehension. Maybe it's good that they don't get implemented. Maggie
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 Ryan
Sent: Saturday, February 07, 2004 3:14 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Academic ERDs vs. Professional ERDs
They are very similiar to class diagrams which are used outside of =
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
> If it is not used outside of academia, then it is either ahead of its =
time
> (due for general adoption) or of absolutely no practical use =
whatsoever.
>
> Given that decision-tree, how long have these concepts been around? =
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 =
relationship
sets.
> > The relations between them seemed very similiar to relations in a =
class
> > diagram.
> > However, I when I look into Erwin and Designer the ERDs there seem =
to be
> > closer to table models. Does anyone use the academic type of ERDs
> > professionally?
> >
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