Re: Primary Key Theory Question

From: Don Verhagen <>
Date: Mon, 29 Mar 2004 10:30:40 -0500
Message-ID: <c49ffr$2gjs97$>

In, Bob Hairgrove <> typed:
: On Sun, 28 Mar 2004 18:56:03 GMT, Ben <>
: wrote:
:: Example 2 - I see a person as an entity. SSN is a good candidate key
:: for a person, but in my situation, that information will frequently
:: be unknown. I see no other candidate keys. Yet if it is poor
:: practice to 'manufacture' a key, what approach should be taken?
: SSN is also not a good choice ... it can change, it is often unknown
: (foreigners to the USA and children don't have SSN), and it is not
: guaranteed to be unique in all cases (don't ask me for the source on
: this ... Joe will have a much better answer<g>)

SSN is *not* a good *primary* key in large personnel databases, working in the industrial temporary services industry, I can tell you have duplicate SSN's (ya know, the same guys sells the fake SSN cards to multiple people). Just a perspective from the employment end. Received on Mon Mar 29 2004 - 17:30:40 CEST

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