UNIVERSITY EXAMINATIONS: 2020/2021
EXAMINATION FOR BACHELORS DEGREE IN INFORMATION
TECHNOLOGY/BBIT/ BAC/ BISF/ BSD
BIT 1209/ BBIT 1209: PRINCIPLES OF DATABASE SYSTEMS
ORDINARY EXAMINATIONS
MODE: PARTTIME/ DISTANCE LEARNING
DATE: DECEMBER 2021 TIME: 2 HOURS
INSTRUCTIONS: Answer Question ONE and Any Other TWO Questions
QUESTION ONE [20 MARKS]
Table banking is a means through which small scale traders can get access to micro loans. It is a
new idea that brings banking services to small scale traders. The loans are mostly used to finance
startup businesses where there is a realistic chance for repayment
NOTE: Use the information provided to answer the question that follow:
• Each borrower and lender must be registered, declare information such as name, and
address.
• A loan starts with a loan request, which contains information about when the loan should
at latest be granted, The total laon amount, and how long the payback period is, and a
description of how the money will be utilized.
• Lenders can commit to an optional portion of the total amount of a loan request.
• When the guarantee for the loan request covers the requested amount, the request is
converted to a loan. If the guaranttee is not enough then the loan request is rejected.
• A borrower can have more than one loan request, and more than one loan at a time, but can
at most make one request per day.
• The loan is paid through an “intermediary”, in this case, Mpesa
• The borrower chooses when he or she will make a payment. Every payment must be
registered in the database with an amount and a date (at most one payment per loan per
day). The lenders share the repayment based on how large a part of the loan they are
responsible for
• If the loan is not repaid before the agreed upon deadline, a new date is agreed. The database
must not delete the old deadline, but save the history (the deadline can be overridden
multiple times).
Required:
a) Use the information (above) to create an E-R model that describes the information
necessary to manage micro loans. [8 Marks]
b) Give a brief description of relationship sets. [4 Marks]
c) Using relevant example, explain the role of an entity. [4 Marks]
d) State the Entity-Relationship scheme for defining constraints. [4 Marks]
QUESTION TWO [15 MARKS]
a) Write an SQL request that returns all the tuples with information on repayments from the
borrower with id equal to 42, and where the lent amount exceeds Ksh.1000. [4 Marks]
b) Using relevant examples, explain FOUR key properties that all database transactions
must have. [8 Marks]
c) Differentiate between authorization and authentication as used in database security.
[3 Marks]
QUESTION THREE [15 MARKS]
a) Explain Four referential actions commonly used when defining foreign keys. [8 Marks]
b) Briefly describe the Two kinds of data independence in Database Management Systems.
[4 Marks]
c) State any Three properties of relations in a relational database. [3 Marks]
QUESTION FOUR [4 MARKS]
a) Describe concurrency control? Further, give appropriate example. [2 Marks]
b) Differentiate between shared lock and exclusive lock as used in transaction management in
the Database Management System. [4 Marks]
c) Define the term design methodology as used in database and explain the main phases of the
database design process. [6 Marks]
d. Explain Three demerits of views in databases. [3 Marks]
