Consider the BANK ER schema in Figure 3.21, and suppose that it is necessary to keep track of different types of ACCOUNTS (SAVINGS_ACCTS, CHECKING_ACCTS, … ) and LOANS (CAR_LOANS, HOME_LOANS, … ). Suppose that it is also desirable to keep track of each ACCOUNT’s TRANSACTIONS (deposits, withdrawals, checks, … ) and each LOAN’s PAYMENTS; both of these include the amount, date and time. Modify the BANK schema, using ER and EER concepts of specialization and generalization. State any assumptions you make about the additional requirements.

Figure 3.21

Transcribed Image Text:

Airport_code City State Name DEPARTURE_ AIRPORT N Leg_no Scheduled_dep_time Scheduled_arr_time FLIGHT LEG AIRPORT N M 1 N ARRIVAL_ CAN_ AIRPORT Instances LEGS LAND Number INSTANCE_OF Airline Type_name Max_seats FLIGHT Company 1 AIRPLANE_ TYPE Arr_time Weekdays DEPARTS N ARRIVES Restrictions FARES Dep_time N Amount TYPE Code FARE Airplane_id Total_no_of_seats No_of_avail_seats Date N ASSIGNED LEG INSTANCE AIRPLANE Customer_name Cphone Seat no RESERVATION Notes: A LEG (segment) is a nonstop portion of a flight. A LEG_INSTANCE is a particular occurrence of a LEG on a particular date. SEAT Figure 3.21 An ER diagram for an AIRLINE database schema.