Re: foundations of relational theory?

From: Marshall Spight <mspight_at_dnai.com>
Date: Sat, 25 Oct 2003 07:34:03 GMT
Message-ID: <LHpmb.22537$Tr4.49381_at_attbi_s03>

"Anthony W. Youngman" <thewolery_at_nospam.demon.co.uk> wrote in message news:Ko91hKAyFDj$EwOn_at_thewolery.demon.co.uk...

>

> My favourite example is always to quote an invoice. How many tables do
> you need in a relational database? One for the invoice itself, one for
> the addresses (two at least, billing and shipping), one for the line
> detail, a couple maybe for the relationships ...

For some customers, ship-to and bill-to are the same address. For others, they are not the same. Let's say you discover that a street name is misspelled on the ship-to address for a customer. You update the record. If ship-to and bill-to are the same address, do you have to do another update? Is it possible to have the two addresses out-of-sync, even though, for this customer, they are the same address?

Marshall Received on Sat Oct 25 2003 - 09:34:03 CEST