Re: looking for 'ER diagram' examples

Edward,

I still like this site for a simple, low level overview of E-R modeling and Relational design.

http://www.utexas.edu/cc/database/datamodeling/index.html

Other people in this forum have criticized it, with some validity, but I have yet to find a site I prefer.

The important thing to remember about E-R modeling, IMO, is that it was invented to provide a vehicle for recording the CONCEPTUAL data model, not the logical or physical data models. As such, the E-R model should reflect a maximum of the relationships between data items that are inherent in the subject matter itself, and not a consequence of design choices in the solution.

In particular, I have seen E-R models (decades ago, now) that were equally valid for a relational database implementation or for an implementation based on networks of records.

--
Regards,
    David Cressey
    www.dcressey.com
"Edward Siebert" <ems362_at_yahoo.com> wrote in message
news:b403cb17.0202191358.430261e8_at_posting.google.com...


> I'm currently taking a database systems class in Chicago, IL and


> am having trouble understanding ER diagrams - the topic currently

> being taught. Unfortunately, the book does not provide many examples

> for how to construct an ER diagram. Does anyone know of any good

> reference material on ER digrams with plenty of examples and problems

> w/ answer key in back of book. I  think I need to practice constructing

> many  diagrams before I can gain a good understanding of  how they work.

>

> Any help would be greatly appreciated! I have a midterm on the

> material coming up at the end of this week.

>

> Edward Siebert