Re: normalization question

Philipp Post wrote:

> Here are the rules:
> 1) There are items, vendors, customers, and boxes.
> 2) Boxes contain items and are sent from one vendor to one customer
> on
> a specific date.
> 3) Items can only be sent once from each vendor to each customer
> ...
> Rule 3 states that items can be sent once from /each/ vendor to /each/
> customer, not once from /any one/ vendor to /any one/ customer. This
> means that item1 could be sent in a box from vendor1 to customer1 and
> that item1 could be sent in a different box from vendor1 to customer2.

Your problem statement is ambiguous. I could read it as meaning you have a single candidate key somewhere of the form {item,vendor,customer} or two keys somewhere of the form {item,vendor} and {item,customer}.

Design by usenet is a futile waste of time. Received on Tue May 05 2009 - 01:09:46 CEST