Charlotte Foust
cfoust at infostatsystems.com
Fri Mar 12 10:40:26 CST 2004
Unfortunately, while zip codes are supposed to be unique, they may be shared among several small towns or a town may have multiple zip codes. Some buildings even have unique zip codes, but generally zip codes belong to post offices. I would say they were not a good candidate for a primary key in dealing with addresses. I've worked with postal databases and seen some of the "duplicate" zips, where several small towns share a post office and a zip code. A further complication is the +four extension. Charlotte Foust -----Original Message----- From: John Clark [mailto:John.Clark at niagaracounty.com] Sent: Friday, March 12, 2004 7:03 AM To: accessd at databaseadvisors.com Subject: RE: [AccessD] question on normalization But, in my case, it would be OK then? I will not have an issue with them being unique. JW Clark >>> ssharkins at bellsouth.net 3/12/2004 9:55:22 AM >>> As a sidebar--sort of--why can't the zip itself be a primary key? ========We're told that ZIP codes aren't unique -- most are, but there those few... I've not encountered it myself, but that's what we're told. ;) Susan H. -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com