Re: Oracle NULL vs '' revisited

From: Frank van Bortel <frank.van.bortel_at_gmail.com>
Date: Sat, 25 Aug 2007 11:33:44 +0200
Message-ID: <faot1e$bl6$1@news6.zwoll1.ov.home.nl>

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Tony Rogerson wrote:

>> The point was to demonstrate the surrogate keys are worthless
>> for purposes of data integrity with most data. What ends up
>> happening is that unique constraints are then built, on top of
>> the surrogate key, in an attempt to do what the surrogate can
>> not.

>
> Oh really?
>
> Then why say this "Natural keys can not change. If it can change IT IS
> NOT A KEY it is
> just a value.".

You seem to have it backwards - the mantra is "if keys can change, it is likely an attribute, not a key".

You prove Daniels point, by demonstrating natural keys change (and *thus* *should* not have been used as keys)
>
> You seem to be under the impression that "Natural keys can not change".
>

The should not, when used in programs. This is different from the fact they change.
Loosely quoted, you stated "ISO country codes are not keys, as they change".

Well - if you knew that from the start (and you should) - if used in a system, that is not expected to cope with those changes, it is acceptable.
For Customs, I'd advise not to use it as a key, but just as a value.

It seems you gentlemen are in agreement, you are just looking at the question at hand from two different angles. - --
Regards,
Frank van Bortel

Top-posting is one way to shut me up...
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