normalization question

#21

Philipp Post wrote:

Quote:

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.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

normalization question

comp.databases.theory comp.databases.theory

Re: normalization question - 05-04-2009 , 06:09 PM