School of Computer Science and Software Engineering. 1st SEMESTER EXAMINATIONS 2008 CITS3240 DATABASES

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1 School of Computer Science and Software Engineering 2008 SURNAME: GIVEN NAMES: STUDENT NO: SIGNATURE: This paper contains:?? pages (including the title page) Time allowed: 2 hours 10 minutes Section A: 1 question Section B: 2 questions Section C: 5 questions (answer FOUR only) TOTAL MARKS: 30 marks 30 marks 40 marks 100 marks You should attempt Section A, Section B and four questions in Section C. The questions should be answered in the supplied answer booklet. PLEASE NOTE Examination candidates may only bring authorised materials into the examination room. If a supervisor finds, during the examination, that you have unauthorised material, in whatever form, in the vicinity of your desk or on your person, whether in the examination room or the toilets or en route to/from the toilets, the matter will be reported to the head of school and disciplinary action will normally be taken against you. This action may result in your being deprived of any credit for this examination or even, in some cases, for the whole unit. This will apply regardless of whether the material has been used at the time it is found. Therefore, any candidate who has brought any unauthorised material whatsoever into the examination room should declare it to the supervisor immediately. Candidates who are uncertain whether any material is authorised should ask the supervisor for clarification.

2 2 Instructions This paper contains three sections totalling 100 marks. Section A is worth 30 marks, Section B is worth 30 marks and Section C is worth 40 marks. Candidates should attempt Section A, Section B and FOUR of the five questions in Section C. If more than four questions are attempted in Section C only the first four will be marked. If you change your mind part way through an answer you should clearly cross the answer out and write NOT ATTEMPTED Please fill in the question numbers in the spaces on the front of the answer booklet.

3 3 Section A 1. Consider a version of a world database with the following schema: CREATE TABLE Country ( code CHAR(3), PRIMARY KEY (code), name CHAR(52), population INT(11), capitalid INT(11) ); CREATE TABLE City ( ID INT(11), PRIMARY KEY (ID), name CHAR(35), countrycode CHAR(3), population INT(11), statecapital ENUM ( Y, N ) ); # 3 letter code of the country # the name of the country # the population of the country # city ID of the national capital # id of the city # the name of the city # 3 letter code of the country # population of the city # Y if city is a state/province/territory capital In the country relation, the capitalid field is a foreign key referencing city.id. The capitalid field identifies the capital city of the country. In the city relation, the countrycode field is a foreign key referencing country.code. The statecapital field identifies cities that are local capitals of states, provinces or territories within a country. Note the national capital is also a state/provincial/territorial capital. Population analysts frequently ask questions of the following form What percentage of the total population of Australia live in the national capital, and what percentage live outside the state/provincial/territorial capitals? where the particular country may change. For example, according to this database, Australia has a total population of 18,886,000 and its capital cities are

4 name population Sydney Melbourne Brisbane Perth Adelaide Canberra Hobart Darwin The percentage of the total population living in the national capital (Canberra) is or 1.71%. The total population living in the capital cities is = Hence the percentage of population living outside the capital cities is or 46.90% Note that the total population of the country is not equal to the sum of the population of all of the cities, because smaller cities are not listed individually. You must write code in each of Java and MySQL to calculate these percentages when you are given the country code. Notice that the input uses the country s code and not its name (e.g. "AUS" rather than "Australia"). For both parts of this question you may assume that the country code is valid. (a) Write two Java methods public double dwellcapital(string code) that returns the percentage of the population of the country identified by code that live in its national capital city and, public double dwelloutside(string code) that returns the percentage of the population of the country identified by code that live outside its state/provincial/territorial capital cities. You may assume that the methods have access to a variable conn that refers to an already-created java.sql.connection. Your Java methods may NOT call the stored procedures of the following question. (15)

5 5 (b) Write two MySQL stored procedures dwellcapital and dwelloutside. Each take one IN parameter code and each have a single OUT parameter. These procedures should calculate the percentage of the population of the country identified by code that live in the national capital city, and the percentage of the population of the country identified by code that live outside its state/provincial/territorial capital cities, respectively. (15)

6 6 Section B 2. Queries in SQL Consider the following schema which represents information in an insurance database. person(driverid:int, name:string, address:string) vehicle(carid:int, model:string, year:year) accident(reportid:int, year:year, location:string) owns(driverid:int, carid:int) involved(driverid:int, carid:int, reportid:int, damageamt:decimal) Note: year is a MySQL type for representing a year in the format CCYY. The meanings of the fields are as follows: Field Meaning Example person.driverid Driver Licence person.name Name John Smith person.address Address 34 ARoad St, ASuburb 6000 vehicle.carid Vehicle Licence vehicle.model Model & Make Rolls Canardly vehicle.year Model Year 1997 accident.reportid Artificial key accident.year Year of accident 2006 accident.location Place of accident 60 BStreet Rd, BSuburb 3400 owns.driverid Foreign key to person.driverid owns.carid Foreign key to vehicle.carid involved.driverid Foreign key to person.driverid involved.carid Foreign key to vehicle.carid involved.reportid Foreign key to accident.reportid involved.damageamt Cost of damage caused by driverid Write MySQL queries for the following tasks: (a) List the names and addresses of all persons involved in an accident in (3) (b) List the model of all vehicles involved in 100 or more accidents between the years of inclusive. The model should only appear once in the list.

7 7 (c) For every individual driver and year, list the number of accidents involving the driver in that year, and the average cost of damage caused by that driver in those accidents. (d) List the worst driver for each year from inclusive. The worst driver in any one year is that driver the causes the highest total cost of accident damage (there may be more than one worst driver in any given year if they cause the same total cost of damage). 3. ER diagramming The Lawrence Wilson Art Gallery at UWA has commissioned the Art-4-U database, that incorporates a schema that captures all the information the gallery needs to maintain. The gallery keeps information about artists, including their name (which are unique), birthplace and their birthdate. For each piece of artwork, the artist, the year it was made, its unique title, its medium (e.g. painting, lithograph, sculpture, photograph), and its price must be stored. Pieces of artwork are also classified into groups of various kinds, for example, portraits, still lifes, works by Picasso, or works of the 19th century; a given piece may belong to more than one group. Each group is identified by a name (like those just given) that describes the group. Finally, the gallery keeps information about its customers; the person s unique name, address, total amount of dollars spent in the gallery, and the artists and groups of art that the customer prefers. Draw a single ER diagram (using the symbols and conventions outlined in lectures) that captures the requirements for this database. Use natural keys where appropriate. Make sure you incorporate any participation and key constraints implied by the specifications. (15)

8 8 Section C 4. Data Mining A Pizza restaurant records the following sales for pizzas with extra toppings, in various combinations. The toppings are mushrooms (M), pepperoni (P) and extra cheese (C). Menu Pizza Extra Item Sales Toppings M P C M & P M & C P & C M, P & C None Total 2000 Complete a market-basket analysis to answer the following questions (a) Find the frequent itemsets with minimum support 40%. (b) Find association rules with minimum confidence 50%. (c) What is the strongest inference we can make about consumer behaviour when choosing extra toppings? (2)

9 9 5. Normalization A company has several sales people (SP) selling hardware products (Prod). Each sales person is attached to a specific department (Dept), that has one manager (Mngr). Any sales person can sell a product, which has a fixed unit price. Each sales person receives a fixed percentage commission (Com) from their total sales (Qnty). An example of typical data is shown in the table below: SP Prod SP Com Year of Dept Mngr Prod Unit Qnty Num Num Name Pcnt Hire Num Name Name Price Baker Scott Hammer Saw Pliers Adams Lopez Wrench Hammer Drill Saw Dickens Scott Drill Pliers Carlyle Scott Wrench Drill Pliers Use the theory of database normalization to identify the functional dependencies and design a well-structured relational database schema to store data of this type. Explain your reasoning. (10) 6. Transactions (a) Explain what a database transaction is, and outline the desirable ACID properties of database transactions. (b) What is a recovery manager of a DBMS and what desirable properties of a transaction does it ensure? (7) (3)

10 10 7. Relational Algebra Consider the following relations containing airline flight information. Flights(flno: integer, from: string, to: string, distance: integer, departs: time, arrives: time) Aircraft(aid: integer, model: string, cruisingrange: integer) Certified(eid: integer, aid: integer) Employees(eid: integer, name: string, salary: integer) Note that the Employees relation describes pilots and other kinds of employees as well; every pilot is certified for some aircraft (otherwise, he or she would not qualify as a pilot), and only pilots are certified to fly. (a) Write a relational algebra query that lists the names of pilots certified for the 747 model of aircraft. (b) Write a relational algebra query that lists the aids of all aircraft that can be used on non-stop flights from Bonn to Madras. (c) Write a relational algebra query to list the names of pilots who can operate planes with a range greater than 3,000 miles but are not certified on the A300 model of aircraft. (2) 8. Database Applications (a) Give a brief outline of how a database abstraction layer such as PHP s MDB2 works, and explain the advantages and disadvantages of using a database abstraction layer. (b) What are the factors that a DBA should consider when deciding whether to use stored procedures and/or client programs (e.g. Java or PHP) in a database application? (6)

School of Computer Science and Software Engineering. 2nd SEMESTER EXAMINATIONS 2007 CITS3240 DATABASES

School of Computer Science and Software Engineering 2nd SEMESTER EXAMINATIONS 2007 SURNAME: GIVEN NAMES: STUDENT NO: SIGNATURE: This paper contains: 9 pages (including the title page) Time allowed: 2 hours