-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/26/07 12:11, Steve Crawford wrote: [snip] > > If we presume that the plate is a key to a vehicle, then we immediately > run into problems as a vehicle can, over time, have several plates > (lost, stolen, changed to vanity...) and a plate can belong, > sequentially, to several vehicles (especially when vanity plates are > transferred to new cars). > > And when you have your char(6) plate-number column, they run out of > numbers and switch to 7-characters requiring changes to all tables that > used the plate as a key. Or you realize that ABC123 could be > ABC123-California, ABC123-Nevada or ABC123-New York (I'm assuming that > AAA999 is a valid format in those states).
We use this as a *non*-unique index: PLATE_NUMBER CHAR(10) PLATE_STATE CHAR(2) PLATE_COUNTRY CHAR(4) The country field could be dropped off and Canada/USA differentiated by the state/province code, but with NAFTA it's possible that Mexican plates will turn up "soon", and there's always the off chance that a European car will show up. (We used to have PLATE_STATE first, but then discovered how many northeasterners don't know what state their vehicle is registered in.) - -- Ron Johnson, Jr. Jefferson LA USA %SYSTEM-F-FISH, my hovercraft is full of eels -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHSzxlS9HxQb37XmcRAh0QAKCLp5aNkoPPs8P5oXQCJ0HI28MNuACeKtFH eECn8XRwrjOqonUuDr8DDH8= =cYiG -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly