Re: Database design, Keys and some other things

From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 27 Sep 2005 07:53:18 -0700
Message-ID: <1127832798.313559.156760_at_o13g2000cwo.googlegroups.com>


David Cressey wrote:
> "Marshall Spight" <marshall.spight_at_gmail.com> wrote in message
> news:1127788646.640736.293230_at_g44g2000cwa.googlegroups.com...
>
> > What's a VIN, then? Are we all imagining them? Are they somehow
> > outside of the real world? Is your bank account id somehow
> > Not Of This Earth? If you bank account didn't have an id,
> > would it be enough to identify it just by the balance?
> > "There is a bank account that is a checking account, with
> > $1,000,000.00 in it." Could I then authenticate myself to
> > the bank by saying, yeah, I'm the guy with the million
> > dollars in the bank. If you forgot your balance, would
> > that mean you lost access to your money?
>
> A VIN, a bank account number, and an SSN are all surrogate keys. We tend
> not to recognize them as such because they are created and managed by an
> agency outside the control of the system we are building or designing. But
> they are just as artificial as PersonId, created by our system when a "new"
> person is introduced to the system.

Definitely! But artificial isn't the same as "not part of the real world." The claim was made that the real world didn't contain predicates that included artificial keys. So I guess that means VIN, bank account number, and SSN are supernatural! Spooky!

The car itself is also artificial, but we don't say it's not part of the real world.

Marshall Received on Tue Sep 27 2005 - 16:53:18 CEST

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