Question:

(a) List four disadvantages of the File Processing System as compared to the Database Systems.

(b) The integrity of a database is enforced by integrity rules. One of these rules, the referential integrity rules, states that the database must not contain any unmatched foreign key values.

(i) Discuss what should happen on an attempt to delete the target of a foreign key reference?

(ii) Discuss what should happen on an attempt to update the primary key of the target of a foreign key reference?

Your discussion should describe the three possible techniques which can be used to deal with the problem, and provide one example for each technique.

(c) List and describe briefly the nine components of a typical database environment.

(d) Explain the difference between external, internal and conceptual schemas. How are these different schema layers related to the concept of logical and physical data independence?