Re: Trying to define Surrogates

On Thu, 17 Aug 2006 23:23:18 GMT, Bob Badour <bbadour_at_pei.sympatico.ca> wrote:

[snip]

>Yes. Often the value depends on other values in the tuple. For instance,
>one can derive the surname, sex and birthdate of an Ontario drivers
>license holder from the drivers license number. This has obvious
>benefits to police officers who might be presented with an altered or
>stolen drivers license.

     One of the things that could be altered is the license number.

>'Intelligent keys' tend to be familiar but not particularly simple or
>stable. The arguments against 'intelligent keys' have more merit as they
>tend to start with all of the problems associated with compound keys and
>unstable keys.

     Quite. My university has rooms designated with a building abbreviation followed by four digits with the first digit being the floor. Some rooms (facilities) have a "9" prepended. If the university ever builds a 90-storey building, the naming scheme will break down.

>However, I note that the province of Ontario seems to think the benefits
>of familiarity outweigh any of the drawbacks. Of course, internally, the
>province must use some other identifier for locating driving
>transcripts. Otherwise, the common practice of assuming one's spouse's
>surname would allow newlyweds to escape their past driving records.

     I wonder what they use. I suspect that the major determinants are date of birth and sex.

Sincerely,

Gene Wirchenko Received on Fri Aug 18 2006 - 02:45:35 CEST