Then we need to keep track of what DVDs each customer currently has checked out. A customer may check
out multiple DVDs at any given time. Rentals are for one or more days, each movie with an individual price
per day. Furthermore we additionally charge 10 baht for movies longer than 2 hours. Maximum rental time
is 4 weeks. The customer gets a bill with movie titles, number of rent days, individual prices and total
amount. The bill looks something like this…”