RE: SQL Table / DDL question on using Unique keyword

Elvis is right, I'd go for the unique constraint. But I have some
business questions. What if there are two Bob Smith's in Kendallville IN
and to find their closest relation you'd have to go back to Cain and Abel?
Let's suppose you're the company that is represented by "Smiling Bob". And
you want to ensure that people aren't getting more than one free sample of
your product. Then typically you would restrict that by PO Box and/or
street address and zip code. And you'd use the ZipCity product by
WorksRight.com to ensure that your zip codes are clean. So now if there
are two Bob Smith's in the town then they both can get a sample. However,
if Bob Smith, and his son-in-law Randy Jones live under the same roof,
then they'll have to fight over who gets the free sample. Of course, the
cat's out of the bag as soon as Randy get's denied for a free sample
because one already went to that address.

worksright might have even more stringent software to ensure that they
don't try to sneak through by misspelling the street name or such thing.
You know, one that will correct addresses upon data entry.

Just a satisfied customer of worksright.

Rob Berendt