MURANG A UNIVERSITY OF TECHNOLOGY

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MURANG A UNIVERSITY OF TECHNOLOGY SCHOOL OF COMPUTING AND INFORMATION TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY UNIVERSITY POSTGRADUATE EXAMINATION 2017/2018 ACADEMIC YEAR FIRST YEAR FIRST

1 MURANG A UNIVERSITY OF TECHNOLOGY SCHOOL OF COMPUTING AND INFORMATION TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY UNIVERSITY POSTGRADUATE EXAMINATION 2017/2018 ACADEMIC YEAR FIRST YEAR FIRST SEMESTER EXAMINATION FOR MASTER OF SCIENCE IN INFORMATION TECHNOLOGY SIT 603: DATABASE DESIGN AND MANAGEMENT DURATION: 3 HOURS DATE: 3 RD MAY, 2018 TIME: 9.00 A.M NOON Instructions to Candidates: 1. Answer Any Four questions. 2. Mobile phones are not allowed in the examination room. 3. You are not allowed to write on this examination question paper. Page 1 of 7

2 QUESTION ONE (25 marks) (a) An important concept in the theory of relational databases is that of a functional dependency. i. Explain what is meant by a functional dependency and give an example (2 marks) ii. Identify two functional dependencies in the following table (A, B and C are names of the columns) A B C a1 a1 a1 b1 b1 b2 c1 c3 c1 (4 marks) (c) (d) (e) Give three reasons why data duplication is still necessary in designing database systems Giving examples, distinguish between: i. Simple and composite attributes ii. Single-valved and multi-valved attributes Explain four strengths of object oriented database managements systems over relational database management systems (8 marks) Describe with an example, one type of problem that can occur in a multi-user environment when concurrent access to the database is allowed QUESTION TWO (25 marks) (a) Refer to the following scenario and Figure A1 that follows. VOX is a company that supplies a number of courses (e.g Visual Basic, Python, SQL, Java) delivered in the form of computer aided learning (CAL) packages that students study on-line. Students first register for an attendance on a course that VOX offer many times, occasionally over the same period of time. Then they access and work through a predefined set of packages in sequence (one at a time). After completing the last package for a course, students are then assessed by a practical test and the result is recorded as pass or fail. VOX log student access to each package recording the following information:- Session ID, The unique identifier whenever the package is accessed Page 2 of 7

3 Student ID, this is the identifier of the student logged into this session Package ID, this indentifies the package a student is logged into Log In Time, this is the unique Login time and date of this session Log Out Time, this is the unique Logout time and date of this session Login Time Left, this is a derived field showing what time is left at the start of a session A student can access a particular package for a maximum of 18 hours over a predefined period after which the package is unavailable to that particular group of students. Each course has a selection of different packages unique to a particular course. The same course can be offered to students many times for example if they wish to restudy. Using any standard ER modeling notation, produce a complete ER model that includes all the entity types highlighted in bold in the scenario resolving any many to many relationships. State any assumptions you made. (15 marks) For each of the following two relational concepts, explain the key ideas behind them and using a sample relation of your own choosing, provide suitable examples: i. Entity integrity (5 marks) ii. Referential integrity (5 marks) QUESTION THREE (25 marks) (a) A company uses the table below to record details of its projects. Each project is attached to a department and runs for a certain duration (in months). The primary key for this table is (projnbr, deptnbr) PROJNBR DEPTNBR PROJNAME DEPTNAME DURATION P01 D03 Web Portal HR Dept 10 P01 D07 Web Portal Sales Dept 10 P02 D07 Data Warehouse Sales Dept 7 P02 D03 Data Warehouse HR Dept 7 i. Give an example of an Update Anomaly that may occur in the table ii. Explain what is meant by partial dependency in a table (2 marks) iii. Identify any partial dependencies in the above table iv. Remove any partial dependencies from the above table by performing a normalization process and show skeletal designs of the resultant tables. (6 marks) Page 3 of 7

4 Database recovery is one of the main services provided by database management systems. i. Describe three types of failure that may occur in a database environment (6 marks) ii. Discuss how the log file is fundamental feature in any recovery mechanism by describing the contents of the log file and how the log file is used in forward and backward recovery. (5 marks) QUESTION FOUR (25 marks) (a) Refer to the following set of SQL statements and the sample tables for this question CREATE TABLE tickets ( ticketno NUMBER, purchasedate DATE, custid NUMBER, fixtureid NUMBER, seated VARCHAR (5) ); CREATE TABLE fixture ( fixtureid NUMBER, fixturedate DATE, opposition VARCHAR (4) ); CREATE TABLE customer ( customerid NUMBER, customername VARCHAR (20), address VARCHAR (20) ); CREATE TABLE seat ( seatid VARCHAR (5), seatingarea VARCHAR (20), Sample tables Table customer seat-type VARCHAR (20) ); CUST ID CUSTNAME ADDRESS R. Sayers Tess IKley Moor P. Smith Preston Capes V. Singh 23 Belle P. Smith Dove Cottage, Stratford Page 4 of 7

5 Sample tables Table seats SEATID SEATINGAREA SEATTYPE C11 West Stand Reserved C12 West Stand C13 West Stand MM3 West Upper MM4 West Upper Reserved MM59 West Upper H105 South Stand Family H106 South Stand Family H107 South Stand G2 East Stand Away G3 East Stand Away K4 North Stand Disabled Table tickets TICKETNO PURCHASEDATE CUSTID FIXTUREID SEATID Dec MM Dec K Dec MM Mar MM Oct C Oct G Oct C Dec H Dec H106 Table fixture FIXTUREID FIXTUREDATE AWAYTEAM Jan-2017 CHEL Jan-2017 MANC Dec-2016 SYND Mar-2017 BORO Oct-2016 WATF April-2017 MANC Page 5 of 7

6 i. Write SQL statement that populate the fixture table with the first 2 rows of the data (4 marks) ii. The CREATE TABLE statements are missing important constraints that could impact on integrity of data in the tables a) List two types of data constraints that are absent in the script (2 marks) b) Write two SQL ALTER statements (one for each type of data integrity constraint) that shows how these data integrity constraints would be added to the script (9 marks) Backups of the database should be taken in order to protect data. Describe five features of good backup strategy (10 marks) QUESTION FIVE (25 marks) (a) Explain briefly what is meant by a weak entity type. Provide an example of a weak entity type using an example of your choice (4 marks) Using the following sample relation and your knowledge of declarative constraints STUDENT (Title, Name, Gender, Address, , Mobile, SID, MID, PROJID, PLACID) Where: SID is the student identifier MID is the identifier of compulsory assigned staff mentor PROJID is the identifier of the optional project selected by the student PLACID is the identifier of the optional industrial placement undertaken by the student. Required: i. Suggest and justify a Primary Key (2 marks) ii. Write the correct SQL code to implement this (c) A company wants to move its current file-based system to a database system. In many ways, this can be seen as a good decision. Identify and describe four disadvantages in adopting a database approach. (8 marks) (d) An embassy records details on interviews of visa applicants in the table below. Interviews are conducted by members of staff in some of the embassy rooms. In any given day, a member of staff tends to use the same room throughout that day. An applicant cannot have two interviews in the same day. Page 6 of 7

7 ApplicantNo. InterviewDate InterviewTime StaffNo RoomNo AP1 13-May R101 AP2 13-May R101 AP3 13-May R200 AP2 22-Sep R200 i. Explain the term candidate key (2 marks) ii. List three candidate keys for the above (6 marks) Page 7 of 7

BCS THE CHARTERED INSTITUTE FOR IT BCS HIGHER EDUCATION QUALIFICATIONS BCS Level 5 Diploma in IT DATABASE SYSTEMS

BCS THE CHARTERED INSTITUTE FOR IT BCS HIGHER EDUCATION QUALIFICATIONS BCS Level 5 Diploma in IT DATABASE SYSTEMS Thursday 28th September 2017 Morning Answer any FOUR questions out of SIX. All questions