A supermarket chain has all of its stores in several regions. Each store is assigned to a single region and a region has many stores. Each store sells a variety of products. A product is identified by its primary key, sku. A product may be sold in many stores. Track the date of a sale and the quantity of the product sold.

question 7: At a local community college, a course may have one prerequisite course (only one!), while a course may serve as the prerequisite for many other courses.