Re: Primary Key

Поиск
Список
Период
Сортировка
От Joshua D. Drake
Тема Re: Primary Key
Дата
Msg-id 20071126104811.1f56f0ef@commandprompt.com
обсуждение исходный текст
Ответ на Re: Primary Key  (Richard Broersma Jr <rabroersma@yahoo.com>)
Ответы Re: Primary Key
Список pgsql-general
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 26 Nov 2007 10:28:03 -0800 (PST)
Richard Broersma Jr <rabroersma@yahoo.com> wrote:

> --- On Mon, 11/26/07, Joshua D. Drake <jd@commandprompt.com> wrote:
> 
> > In "theory" the item that would be a natural key
> > in this instance is the VIN. You would of course have
> > to make some kind of allowance for cars that don't
> > have a VIN (nothing in the last what...
> > 50 years?).
> 
> So this is why the service stations always record my cars VIN number
> when I show up for oil changes. ;)  Ofcourse, there is a whole
> industry built around auto theft where they restamp the stolen car
> with a differnt vin number.  I wonder if these stolen cars end up
> with duplicated VIN numbers or if the VIN's they are given do not
> pass the the VIN check-sum (if such a think exists).

They may end up with duplicate VINs but that isn't really relevant as
at that point we know that one of the two (or six or whatever) cars are
invalid, thus the "natural" key is still valid and designed to alert us
if there is any potential problem :)

Sincerely,

Joshua D. Drake


> 
> Regards,
> Richard Broersma Jr.
> 
> ---------------------------(end of
> broadcast)--------------------------- TIP 1: if posting/reading
> through Usenet, please send an appropriate subscribe-nomail command
> to majordomo@postgresql.org so that your message can get through to
> the mailing list cleanly
> 


- -- 

      === The PostgreSQL Company: Command Prompt, Inc. ===
Sales/Support: +1.503.667.4564   24x7/Emergency: +1.800.492.2240
PostgreSQL solutions since 1997  http://www.commandprompt.com/
            UNIQUE NOT NULL
Donate to the PostgreSQL Project: http://www.postgresql.org/about/donate
PostgreSQL Replication: http://www.commandprompt.com/products/

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQFHSxTtATb/zqfZUUQRAoDbAJ9h+NcHeyj7b1dmFAXl5uSWUbHzJwCfVOSW
vBFs5lpCXrgeCwOu0wud9S8=
=9AfY
-----END PGP SIGNATURE-----

В списке pgsql-general по дате отправления:

Предыдущее
От: "Garber, Mikhail"
Дата:
Сообщение: Re: Primary Key
Следующее
От: Glyn Astill
Дата:
Сообщение: Re: replication in Postgres