Movies are presented on a ballot to the Academy as, for example, The Lion King - G, where the last character(s) represent the rating. Some intrepid soul must enter the information in the database to include this title as formatted, the rating, the year, the lead actor, the lead actress, the director, and the genre. Comment on how each of the four types of constraints could be used to help the person entering the data to produce only valid entries for the movie rating.