Question:

This Question refers to the database schema given in the Appendix.

(a) The integrity of a database is enforced by integrity rules. Discuss what should happen on an attempt to delete the target of a foreign key reference (for example, to delete a lecturer in the LECTURER table who lectures at least one unit listed in the TIMETABLE table)? Your discussion should describe the three possible techniques which can be used to deal with the problem, and provide one example for each technique by using the above tables.

(b) Using the database schema, express the following queries in SQL:

(i) Create the TIMETABLE table including the primary and foreign key constraints in the code. Make any assumption you want to make.

(ii) Insert the first row in the TIMETABLE table and make any assumption.

(iii) Modify the code value to Workshop for the above record created assuming that the rest of the values have already been created.

(iv) Find the numbers of students who have achieved one or more final grade greater than 14.

(v) Find the student number, unit number and final grade for those students attending units run by the departments named ‘computing' or
‘accountancy'.