On 15 Apr 2002 at 14:20, Nick Fankhauser wrote:

> As a general rule, a primary key (or any relationship key) should not
> contain a value that means something beyond its use in relating entities.
> The problem is that if a field describes an object, the day may come when
> you want to change the description, but you *never* want to change the
> field that identifies the record and relates it to other records.

FWIW, I would recommend not using business values as a primary key (and by 
extension, as a foreign key).  Business values are just that: business 
values.  Sure, put unique constraints on business values if you want.  
Just don't make them a primary key or a foreign key.
-- 
Dan Langille
The FreeBSD Diary - http://freebsddiary.org/ - practical examples


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