Re: "Structured" Entity-Relationship Model?

> Using the SERM example on the wikipedia page, the graph says every
> order has N order items, and every order item has 1 order. Although
> drawn as just one line, that line states two rules, mutually
> dependent: a cycle. (Try using DRI to enforce them.)

And just two (mutually co-dependent) constraints wouldn't be enough to correctly implement the semantics, as far as I understand. But database design books don't seem to explain it either. At least those that I have access to. Or am I just blind?

This issue (it's "just" a 1:n relationship with n>0, right?) must be as old as the relational database model itself (fourty years now?).

I've tried to google for the relevant terms, and couldn't find a documented example for a correct, tested solution. Or is it just that you need to know *the* terms to search for?

Does someone in this group know of a book (or an online document) that shows how to *correctly* implement such things? And maybe one that also gets other things (that I haven't stumbled over yet) *right*? Something like "database design caveats that most textbooks conveniently ignore"?

TIA, Sincerely,

Wolfgang Received on Tue Apr 30 2013 - 16:30:54 CEST