Seeking ERD/Schema resources

Hi all. I’ve been working diligently through several of the popular
tomes on RoR:

  • Beginning RoR E-Commerce
  • The Money Train (Benjamin C.)

I’ve learned lots, however these books cover selling one type of
product (i.e. a book). One thing is eluding me: I’m trying to develop a
schema for a music store that offers products with options (i.e.
Filetype, Length) and I’m running into a conceptual brickwall.
Specifically the step that happens before I even turn on the computer.
The diagram of how it all ties together.

Mr. Curtis covers to this in (the excellent) Money Train, but his
example is incomplete (as advertised) and just out of my depth. It
would probably be of great benefit to someone with a couple more
chapters of reading than I have.

Can anyone recommend any online (or offline) resources that cover a
more complex store schema (not necessarily in RoR)?

Thanks in advance.
Don C.


I’m glad there are still folks that think about the modeling and design
essential to quality system development.

Of course, I am a bit biased in this respect given that it is a large
part of
what I do in my day to day work !!!

If you are looking for a good source of models then I would suggest
“Enterprise Patterns and MDA : Building Better Software with Archetype
Patterns and UML” by Jim Arlow and Ila Neustadt (Addison-Wesley, ISBN
0-321-11230-X). It covers the major “archetypal patterns” which you
modify to you own particular requirements. Among those you might be
interested in from a “store” viewpoint are Customer, Product, Inventory,
Order, Quantity and Money. There is a sample chapter (on “Money”)
at -

I hope this isn’t too rigorous a work for you.

Ironically, I did a data model for an online record store a number of
ago. And one of my current customers is in the online music business
So I’m fairly familiar with the challenges you may face : especially
relating music to genres and subgenres !


Phil Nelson
ScotDB Limited