L' Eomot Inversé (4/25/2013)
But I have a minor quibble: if this is a business rule, it should be enforced by the schema if possible, not by code; and this is a classic example of a rule that can be enforced by a check constraint.
For a production implementation, I fully agree that a trigger, even a well-coded one, would be a terrible way to implement this rule.
But for a QotD about triggers, using a CHECK constraint would not have been a very smart choice! 😉