Re: primary key and existing unique fields

Can you please elaborate on the point you just made as to why the primary
key should not relate to the data (even for a case when there is an existing
unique field that can be used to identify the record)

>From: "Joshua D. Drake" <jd@commandprompt.com>
>To: Sally Sally <dedeb17@hotmail.com>
>CC: pgsql-general@postgresql.org
>Subject: Re: [GENERAL] primary key and existing unique fields
>Date: Tue, 26 Oct 2004 09:48:50 -0700
>
>Sally Sally wrote:
>>Hi all,
>>I am wandering about the pros and cons of creating a separate serial field
>>for a primary key when I already have a single unique field. This existing
>>unique field will have to be a character of fixed length (VARCHAR(12))
>>because although it's a numeric value there will be leading zeroes. There
>>are a couple more tables with similar unique fields and one of them would
>>need to reference the others. Does anybody see any good reason for adding
>>a separate autoincrement primary key field for each table? or either way
>>is not a big deal.
>
>Your primary key should not be directly related to the data being stored.
>Outside of the fact that it is the primary reference or the row.
>
>Sincerely,
>
>Joshua D. Drake
>
>
>
>>Sally
>>
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