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Part B - 10 Short Answer Questions (50 marks in total, the value for each question is indicated) Question 1 (4 marks) (a) In the context of relational algebra what is meant by the term 'unary operator"? (b) List the names of two unary relational algebra operators. Question 2(4 marks) (a) Describe what is meant by the term 'data independence. (b) How does a database management system achieve data independence? Question 3 (4 marks) (a) What is a view? (b) What is the difference between a view and a base relation? Question 4(9 marks total) (a) Define the term 'foreign key'(2 mark) (b) Draw and populate 2 sample tables to illustrate the concept of a foreign key.(4 marks) (c) Referring to the 2 sample tables describe how they illustrate the use of a foreign key.(3 marks) Question 5(8 marks total) Draw an Entity Relationship Diagram to illustrate the following schema: Store(store_id, storename, suburb) Staff(Staff_id, surname, first_name, phone_number, date_of_birth, store_id*) Merchant(merchant_id, first_name, last_name, phone number) MerchantInterests(merchant id*, store id*) Assume that staff can only work at one store. A store employs many staff. A merchant can be the owner of many stores and a store can be owned by many merchants