> A artificial does not protect against duplication. > > That's it, in a nut shell. There is no argument there. That is why you > don't use artificial keys. Sure, but in many cases natural primary keys simply do not exist. (People being the prime example.) Many examples of what are proposed as natural primary keys are actually not--they are very often non-unique or prone to change, or both. Relational theory is quite powerful, but its dogmatic application often conflicts with the mess that is the real world. Given a choice between a synthetic primary key and a sloppy approximation of a natural one (or even an accurate-looking one handed to me by a clean-shaven guy in an expensive suit), I'll take the synthetic one because my experience has been that over the long term it will cause fewer problems by far. -- Scott Ribe scott_ribe@xxxxxxxxxxxxxxx http://www.killerbytes.com/ (303) 722-0567 voice
