Answer Section B questions in Answer Book B B4. Consider the following scenario for a garage selling and servicing cars and answer the questions in parts (a) and (b) below. The following rules describe the garage in more detail. A customer engages with the garage either as a buyer or by having their car(s) serviced (or both). i) A salesperson may sell many cars, but each car is sold by only one salesperson. ii) Each salesperson or mechanic has a name and last name. Cars have a number plate, make and model as well as registration year. Customers have a first and last name as well as an address. iii) A customer may buy many cars, but each car is bought by only one customer. A sale takes place on a specific date. iv) A salesperson writes a single invoice for each car he or she sells. v) A customer receives an invoice for each car he or she buys. vi) When a customer takes one or more cars in for repair or service, one service ticket is written for each car. A service takes place on a specific date and customers receive comments on what has been done. vii) A car brought in for service can be worked on by many mechanics, and each mechanic may work on many cars. Each mechanic spends a certain amount of time on a job, called an assignment, and has an associated rate. a) Draw an entity relationship diagram for the Car Dealership scenario using a suitable notation. Your answer must show the entities and their relationships. Cardinalities and optionality between entities MUST be shown. State any additional assumptions you are making. (14 marks) b) Design a set of tables derived from the Entity-Relationship Diagram in part (a). Highlight ALL primary and foreign keys and show a few rows of sample data (no more than four rows per table). A2. a) Describe the main recovery techniques that many DBMS (Database Management Systems) provide to safeguard and protect data as a result of EACH of the following events: i) Human Error: an employee may unintentionally delete some data or may have used a routine that has modified the data unknowingly in a way that would cease the DBMS from interacting with the database effectively. ii) Network failure where a connection of a database to a shared network has been interrupted. iii) Database software failure: this might be the result of the DBMS crashing unexpectantly. iv) Media Failure with possible loss of all or some data. v) National catastrophe such as an earthquake or flood meaning the entire operation of the host DBMS is lost. (15 marks) b) Describe the security measures and precautions that a DBA (Database Administrator) must have in place to prevent the database from being subject to hacking, for example, someone trying to steal data. (5 Marks) c) A data dictionary holds information that is crucial for the correct operation of a database. If the data dictionary is lost, the database cannot operate. Describe the contents of a typical data dictionary. (5 marks) (11 marks)