Re: Surrogate Key vs Production Key

On Wed, 13 Oct 2004, damorgan_at_x.washington.edu wrote:
> Galen Boyer wrote:
>

>> On Mon, 11 Oct 2004, damorgan_at_x.washington.edu wrote:
>>
>>>Galen Boyer wrote:
>>>
>>>>What does one do when the "natural keys" are actually
>>>>different based on the source?  Maybe someone needs to define
>>>>a "natural key".  Seems to me, it is a key that some other
>>>>system has already defined.
>>>
>>>The natural key is well defined by the work done by Date and
>>>Codd.  That which uniquely defines a record in one set does
>>>not necessarily define a unique record in another set.
>> So, what does one do when there are multiple sources of data.
>> Suppose you are storing loans for customers who want to login
>> to your analytic application and analyze their loans.  One
>> customer's representation of the loan is a string, one is a
>> number and one has a two-part key.  Whats the "natural key"?

? We do have multiple natural keys. I'm wondering how to solve that. (Well, I've solved it with a key translation set of tables and a surrogate key for my primary keys, but I'd like to hear the "natural key" proponents answers)

> What is a natural key in one system may not be in another. To
> try to treat it otherwise is tortured logic.

But I'm talking about a well-known financial instrument, like a loan or a bond. Why is the "natural key" theory not supporting my needs?

-- 
Galen Boyer