Assignment #2. CS Spring 2015 Due on Friday, June 19, 2015, 9 AM For instructions on how to submit your assignment check the course website.

Transcription

1 Assignment #2 CS Spring 2015 Due on Friday, June 19, 2015, 9 AM For instructions on how to submit your assignment check the course website. 1

2 CS Spring 2015 : Assignment #2 QUESTION 1. Question 1. Consider the following database schema: Emp(eid : integer, ename : string, age : integer, salary : real) W orks(eid : integer, did : integer, pct time : integer) Dept(did : integer, budget : real, managerid : integer) Write SQL statements to answer the tasks that follow: 1. Create the Emp table. CREATE TABLE emp ( eid INTEGER PRIMARY KEY, ename VARCHAR(20), age INTEGER, salary DECIMAL(8, 2) ); 2. Insert the following instance into Emp. Emp eid ename age salary 1 Donald Duck 35 18, Minnie Mouse 19 9, Mickey Mouse 24 20, Goof y 20 13, 000 INSERT INTO emp VALUES (1, Donald Duck, 35, 18000), (4, Minnie Mouse, 19, 9000 ), (2, Mickey Mouse, 24, ), (3, Goofy, 20, ); Page 2 of 11

3 CS Spring 2015 : Assignment #2 QUESTION Try altering the Emp table to define a constraint that will ensure that every employee makes at least $10,000. ALTER TABLE emp ADD CONSTRAINT check_salary CHECK (salary > 10000); 4. Give Minnie a salary increase of $2,000. UPDATE emp SET salary = salary WHERE ename LIKE %Minnie% ; 5. Alter the Emp table to define a constraint that will ensure that every employee makes at least $10,000. ALTER TABLE emp ADD CONSTRAINT check_salary CHECK (salary > 10000); 6. Create the Dept table. CREATE TABLE dept ( did INTEGER PRIMARY KEY, budget DECIMAL(9, 2), managerid INTEGER ); 7. Alter the Dept table to define a foreign key constraint (with cascade delete) on managerid, referencing Emp table. ALTER TABLE dept ADD CONSTRAINT manager_fk FOREIGN KEY (managerid) REFERENCES emp (eid) ON DELETE CASCADE; 8. Insert a valid tuple in Dept. INSERT INTO dept VALUES (1, , 1); 9. Delete all tuples from Emp. DELETE FROM emp; Page 3 of 11

4 CS Spring 2015 : Assignment #2 QUESTION List all tuples from Dept. SELECT * FROM dept; 11. Create the W orks table and define foreign key constraints on eid and did, referencing Emp and Dept tables, respectively. CREATE TABLE works ( eid INTEGER REFERENCES emp ON DELETE CASCADE, did INTEGER REFERENCES dept ON DELETE CASCADE, pct_time INTEGER, PRIMARY KEY (eid, did) ); 12. Populate all 3 relations with 3 to 6 valid tuples. INSERT INTO emp VALUES (1, Donald Duck, 35, 18000), (4, Minnie Mouse, 19, ), (2, Mickey Mouse, 24, ), (3, Goofy, 20, ); INSERT INTO dept VALUES (100, , 1), (200, , 1), (300, , 3); INSERT INTO works VALUES (1, Page 4 of 11

5 CS Spring 2015 : Assignment #2 QUESTION , 310), (1, 200, 120), (4, 300, 410), (3, 300, 180), (2, 200, 190); 13. Delete all information about employees whose salaries exceed that of the manager of one or more departments that they work in. Ensure that all the relevant integrity constraints are satisfied after your updates. DELETE FROM emp E WHERE E.eid IN (SELECT W.eid FROM works W, emp M, dept D WHERE W.did = D.did AND D.managerid = M.eid AND E.salary > M.salary); Page 5 of 11

6 Question 2. Consider the following database schema: P roduct(manufacturer, Model, T ype) Computer(M odel, Speed, RAM, HD, CD, Screen, P rice) P rinter(model, Color, T ype, P rice) and its instance: P roduct M anuf acturer M odel T ype A 1001 pc A 1002 pc A 1003 pc B 1004 pc B 1006 pc B 3002 printer B 3004 printer C 1005 pc C 1007 pc D 1008 pc D 1009 pc D 1010 pc D 2001 laptop D 2002 laptop D 2003 laptop D 3001 printer D 3003 printer E 2004 laptop E 2008 laptop F 2005 laptop G 2006 laptop G 2007 laptop H 3005 printer I 3006 printer Computer M odel Speed RAM HD CD Screen P rice x x x x x x x x x x x x x x x x x x P rinter Model Color T ype P rice 3001 true ink jet true ink jet f alse laser true laser f alse ink jet true dry 129 Page 6 of 11

7 Write SQL queries to answer the following: 1. Which laptop models are shown in the P roduct relation? SELECT DISTINCT model WHERE model IS NOT NULL AND type = laptop ; 2. Find the set of all manufacturers ordered alphabetically. SELECT DISTINCT manufacturer WHERE manufacturer IS NOT NULL ORDER BY manufacturer ASC ; 3. Which computer models appear in the database? SELECT DISTINCT model FROM computer WHERE model IS NOT NULL; 4. Which computer models use 256 MB of RAM? SELECT DISTINCT model FROM computer WHERE ram = 256 AND model IS NOT NULL; 5. Which computer models cost less than $1100? SELECT DISTINCT model FROM computer WHERE price < 1100 AND model IS NOT NULL; 6. Which laptop models have a HD of at least 50 GB and cost less than $1400? SELECT DISTINCT p.model p, computer c WHERE p.model = c.model AND p.type = laptop AND c.hd >= 50 AND c.price < 1400; Page 7 of 11

8 7. Which laser printer models can print color documents? SELECT DISTINCT model FROM printer WHERE color = true AND type = laser AND model IS NOT NULL; 8. Which laptop models that have more than 256 MB of RAM are produced by manufacturer D? SELECT DISTINCT p.model p, computer c WHERE p.model = c.model AND p.type = laptop AND p.manufacturer = D AND c.ram > 256; 9. Which computer models that have more than 256 MB of RAM are produced by manufacturer D? SELECT DISTINCT p.model p, computer c WHERE p.model = c.model AND p.manufacturer = D AND c.ram > 256; 10. Which laptop models cost less than $1200? SELECT DISTINCT p.model p, computer c WHERE p.model = c.model AND p.type = laptop AND c.price < 1200; 11. Which manufacturers produce personal computers and printers? SELECT DISTINCT p1.manufacturer p1, product p2 WHERE p1.manufacturer = p2.manufacturer AND p1.type = pc AND p2.type = printer ; 12. Which manufacturers produce all the product types? Page 8 of 11

9 SELECT DISTINCT manufacturer WHERE manufacturer IS NOT NULL GROUP BY manufacturer HAVING Count(DISTINCT type) >= ALL (SELECT Count(DISTINCT type) ); 13. Which manufacturers supply only personal computers? WHERE type = pc AND manufacturer IS NOT NULL EXCEPT WHERE type <> pc ; 14. Which manufacturers supply only one type of product? WHERE manufacturer IS NOT NULL GROUP BY manufacturer HAVING Count(DISTINCT type) = 1; 15. You want to buy: a personal computer with at least 1024 MB of RAM and a CD with 56x, and a laptop with a screen larger than 15, and a printer cheaper than $300 all produced by the same manufacturer. Which manufacturers should you consider? SELECT DISTINCT pc.manufacturer FROM (product natural JOIN computer) AS pc, (product natural JOIN computer ) AS l, (product JOIN printer ON product.model = printer.model) AS pr WHERE pc.manufacturer = l.manufacturer AND pc.manufacturer = pr.manufacturer AND pc.type = pc AND pc.ram >= 1024 AND pc.cd = 56x Page 9 of 11

10 AND l.type = laptop AND l.screen > 15 AND pr.price < 300; 16. What HD sizes are common to at least 2 computers? SELECT hd FROM computer GROUP BY hd HAVING Count(DISTINCT model) >= 2; 17. Which manufacturers sell more than one computer that has a processor speed of less than 3 GHz? natural JOIN computer WHERE speed <= 3 AND manufacturer IS NOT NULL GROUP BY manufacturer HAVING Count(DISTINCT model) > 1; 18. Which manufacturers sell the fastest computers? SELECT DISTINCT manufacturer natural JOIN computer WHERE speed = (SELECT Max(speed) FROM computer) AND manufacturer IS NOT NULL; 19. Which manufacturers do not sell laptops? SELECT DISTINCT manufacturer WHERE manufacturer NOT IN ( WHERE type = laptop ); 20. Which manufacturers offer at least 2 laptop models? WHERE type = laptop AND manufacturer IS NOT NULL GROUP BY manufacturer HAVING Count(DISTINCT model) >= 2; Page 10 of 11

11 21. Which manufacturers offer exactly 3 types of personal computers? WHERE type = pc AND manufacturer IS NOT NULL GROUP BY manufacturer HAVING Count(DISTINCT model) = 3; 22. You need to buy: a computer that has at least 1024 MB of RAM, a processor speed of 3 GHz or 3.5 GHz, a HD of at least 160 GB, and a color printer. Which manufacturers can offer you this combination and at what total price? SELECT DISTINCT p1.manufacturer, c.price + i.price AS total_price FROM computer AS c, product AS p1, printer AS i, product AS p2 WHERE p1.manufacturer = p2.manufacturer AND c.model = p1.model AND c.ram >= 1024 AND c.hd >= 160 AND ( c.speed = 3 OR c.speed = 3.5 ) AND i.model = p2.model AND i.color = true; Page 11 of 11