CITS3240 Databases Mid-semester 2008

Transcription

1 CITS3240 Databases Mid-semester 2008 This paper consists of 6 pages and 3 questions. You should complete every question (total of 40 marks). Answer each question in the space provided. Name: Student Number: Question 1 (12 marks) Draw a single ER diagram that captures the following information about the operations of a pharmaceutical company, Prescriptions-R-Us. Patients are identified by their SSN, and their names, addresses and ages must be recorded. Each pharmaceutical company is identified by name, and has a phone number. For each drug, the trade name and formula must be recorded. Each drug is sold by a given pharmaceutical company, and the trade name identifies the drug uniquely from among the products of that company. Each pharmacy has a name, address and phone number. Each pharmacy sells several drugs and has a price for each. A drug could be sold at several pharmacies, and the price could vary from one pharmacy to another. A patient can have several prescriptions for several drugs, and each prescription has a date and a quantity associated with it. You can assume that if same patient has been prescribed the same drug several times, that only the last prescription details needs to be stored. Pharmaceutical companies have long term contracts with pharmacies. A pharmaceutical company can contract with several pharmacies, and a pharmacy can contract with several pharmaceutical companies. For each contract there is a start date, an end date, and the text of the contract. Pharmacies appoint a supervisor for each contract. There must always be a supervisor for each contract, but the contract supervisor can change over the lifetime of the contract. Notes: Draw your ER Diagram in the style adopted in the textbook (not your own favourite style). Draw it as one connected picture, not as a collection of isolated pieces. Use natural keys where possible. Recall you are being asked for an ER Diagram, and not for a database schema! PUT YOUR ANSWER ON THE NEXT PAGE 1

2 ANSWER QUESTION ONE HERE 2

3 Question 2 (12 marks) Consider the following DB schema recording films that are loan to customers. The various id fields in the relation are keys to the same-named fields found in the other two entities. Customer (cid: integer, name: string, address: string, age: integer) Film (fid: integer, name: string, genre: enum, rating: enum) OnLoan (cid: integer, fid: integer, collect: date, return: date) 1. The film genres available are comedy (C), horror (H) and drama (D). The film ratings are G, PG, M, MA and R. Write the MySQL statements necessary to create the table Film. CREATE TABLE film ( fid INT, name VARCHAR(50), genre ENUM ( C, H, D ), rating ENUM ( G, PG, M, MA, R ), PRIMARY KEY (fid) ); 3

4 2. Write the MySQL statement needed to add a new customer Steven Jobs with customer id 123, living at 1 Infinite Loop Cupertino CA and aged 53. INSERT INTO customer VALUES (123, Steven Jobs, 1 Infinite Loop Cupertino CA 95014, 53) Don t miss out the word VALUES. 3. Write the MySQL statements necessary to create the table OnLoan (you may assume that the other tables have been created) in such a way that referential integrity is assured and that the entry is removed if the customer leaves or the film recording is lost or damaged. CREATE TABLE OnLoan ( cid INT, fid INT, collect DATE, return DATE, PRIMARY KEY (cid, fid), FOREIGN KEY (cid) REFERENCES customer (cid) ON DELETE CASCADE, FOREIGN KEY (fid) REFERENCES film (fid) ON DELETE CASCADE ) Engine = InnoDB; Key points here are to declare the foreign keys, the behaviour on delete and to remember that MySQL needs the InnoDB engine to enforce referential integrity. 4

5 Question 3 (16 marks) Consider the following schema used widely in the textbook (where sid and bid in Reserves are foreign keys to the same fields in Sailors and Boats). Sailors(sid: integer, sname: string, rating: integer, age: real) Boat(bid: integer, bname: string, colour: string) Reserves(sid: integer, bid: integer, day: date) Write single MySQL queries to do each of following things: 1. List the names (in alphabetical order) and ratings of sailors who have reserved boat number 103. SELECT S.sname, S.rating FROM sailors S, reserves R WHERE S.sid = R.sid AND R.bid = 103 ORDER BY S.sname; 2. Find the age of the youngest sailor who is at least 18 years old for each rating level with at least two such sailors. SELECT S.rating, MIN(S.age) FROM Sailors S WHERE S.age >= 18 GROUP BY S.rating HAVING COUNT(*) > 1; 5

6 3. Find the names of sailors who have not reserved a red boat. SELECT S.sname FROM Sailors S WHERE S.sid NOT IN (SELECT R.sid FROM Reserves R, Boats B WHERE R.bid = B.bid AND B.colour = red ); 4. Make a list containing the name and colour of every boat, along with the name of the sailor who most recently reserved that boat, and the date of that reservation. SELECT B.bname, B.colour, S.sname, R.day FROM sailors S, reserves R, boats B WHERE R.bid = B.bid and R.sid = S.sid AND R.day = (SELECT MAX(R2.day) FROM reserves R2 WHERE R2.bid = B.bid) END OF TEST PAPER 6