"Henning Hraban Ramm" <[EMAIL PROTECTED]> schrieb: > Just to add another example where I use manual PKs all the time (and > wouldn't like to change that): > > Geographical lookup tables for countries or cities (PK: TLD, car/state/ > postal code) - > I want to find "D" or "de" in my address entry, not some index that I > would have to look up itself! > > In some applications even product IDs (e.g. ISBN, EAN...) make sense > as PKs. > E.g. in one of my web projects a publishing house uses short codes for > its magazines; a lot of other tables relate to them; it's only that > one lookup table that uses these codes as PK, but so we get > understandable relations everywhere and reduce the need for joined > queries, because the editors know their codes. >
Very good examples, I think. And all cases where the PK wouldn't ever change, right? Or if it did (the transition to postal codes with 5 digits in Germany some years ago) it would be a big thing anyway. Your magazine short code example reminds me of all the large bibliographic databases using the "CODEN" of scientific journals as a means of uniquely identifying them. Don't know if those were used as PKs in the strict sense, though. Greetings, Sibylle -- Dr. Sibylle Koczian _______________________________________________ Post Messages to: Dabo-users@leafe.com Subscription Maintenance: http://leafe.com/mailman/listinfo/dabo-users Searchable Archives: http://leafe.com/archives/search/dabo-users This message: http://leafe.com/archives/byMID/[EMAIL PROTECTED]
