DIPLOMA IN INFORMATION SYSTEM & COMPUTER SCIENCE
Mid Semester Test
IT244 – Database Management System
TIME ALLOWED: 1 hour 5 minutes
QUESTION AND ANSWER BOOKLET
INSTRUCTIONS:
1. Answer ALL questions on this paper.
2. This paper is divided into TWO Sections:
A: Multiple Choice
…………………..
20 marks
B: Short and Long Answers
………………….
30 marks
TOTAL:
50 marks
Student Name: ____________________________
Student Number: _____________________
Study Program (CS or IS): _____________
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SECTION 1: MULTIPLE CHOICES:
Circle the one and only best answer.
1. Database:
A. Is a self describing of data.
B. Is a basement for storing data.
C. Is the collection of data about related sets of things.
D. Is a program to help users to make decision.
2. The smallest unit in database structure is:
A. Object
B. Field
C. Character
D. Element
3. DBMS is the___________________ to manage the collected data.
A. Software
B. Freeware
C. Shareware
D. Hardware
4. Database have the following characteristics:
A. They represent same aspects of the real world
B. The are logically coherent and have some meaning
C. The are created for specific purposes
D. All of the above
5. Data types for Credit Limit should be:
A. Text
B. Currency
C. Character
D. Integer
6. Repetition of Data leads to:
A. Data Faulty
B. Data Inconsistency
C. Data Overhaul
D. Data Manipulation
7. Data are all in one database but kept in a separate units or ____________:
A. Tables.
B. Fields
C. Objects
D. Platform
8. Entering data into the database is known as
A. Database populating
B. Database building
C. Database feeding
D. Database striking
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9. Concurrent Access means:
A. Access now
B. Multiple access
C. Access one by one
D. Access everything
10. The advantage of DBMS over Traditional File Management System is ____________ to
manage stored data.
A. Durability
B. Flexibility
C. Responsibility
D. Validity
11. Row in a relational Database Table is referred to as
A. Relation
B. Table
C. Tuple
D. Attribute
12. System Maintenance In Database Planning is:
A. Enhancement.
B. Entertainment
C. Encouragement
D. Enrichment
13. DBMS expectations are to:
A. Create data
B. Store Data
C. Query Data and
D. Control Access to Data
E. All of the above
14. Fields in Relational Database terminology mean:
A. Attributes
B. Records
C. Element
D. Data
15. Oracle and Access are examples of :
E. Relational
F. Network
G. Object Oriented
H. Environment
16. SQL stands for:
F. Semi Query Language
G. Structured Query Language
H. Strict Query Language
I. Sum Query Language
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Use this information to answer question 17 to 19
A.
B.
C.
D.
E.
Department (Dept#, Name, MgrEmp#, MgrStartDate)
Dept_Location( Dept#,Location#)
Employee (Emp#, Name, Salary, BDate, Dept#)
Project (Proj#, Name, Budget)
Works_On (Emp#, Proj#, Hours, PerformanceRating)
17. Which component shows a Primary Key
A.
A
B.
AB
C. ABC
D. ABCD
E.
ABCDE
18. Which component has two primary keys
A.
A&B
B.
B&C
C. C & D
D. B & E
E.
D&E
19. Emp# is a foreign key in
A.
A
B.
B
C. C
D. D
E.
E
20.
A.
B.
C.
D.
Logical Database design phase focus on the:
Attributes for each Entity
E/R Diagram for the Database
Data Types of each Attributes
Relationships among each Entity
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SECTION 2: Shirt and Long Answers
30 marks
1. What is DBMS and its three main components? (3)
DBMS is the is a software system designed to allow the definition, creation, querying, update, and
administration of databases. Well-known DBMSs include MySQL, PostgreSQL, SQLite, Microsoft
SQL Server, Microsoft Access, Oracle, Sybase, dBASE, FoxPro, and IBM DB2. A database is not
generally portable across different DBMS, but different DBMSs can inter-operate by using standards
such as SQL and ODBC or JDBC to allow a single application to work with more than one database.
Any Three of Hardware, Software, People Data and Procedure
2. Define DDL and DML with their roles in Database Design. (2)
Data definition language - defines data types and the relationships among them
Data manipulation language - performs tasks such as inserting, updating, or deleting data
occurrences
3. Give one entity with two attributes that likely to be found in a Hospital Database System. (2)
Doctors with name and DOB
Wards with number and name
4. What are the two rules of thumb to help in identifying Entity and Relationships (2)
Two rules of “thumb” to help in identifying Entity and Relationship type are:
- An Entity type corresponds to NOUN
- A Relationship type corresponds to VERB
5. Explain the structure of a Client-Server Systems.(1)
In a network, the client/server model provides a convenient way to interconnect programs that are
distributed efficiently across different locations. Computer transactions using the client/server model
are very common. For example, to check your bank account from your computer, a client program in
your computer forwards your request to a server program at the bank. That program may in turn
forward the request to its own client program that sends a request to a database server at another
bank computer to retrieve your account balance. The balance is returned back to the bank data client,
which in turn serves it back to the client in your personal computer, which displays the information for
you.
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6. Define with examples the term Composite Attributes. (2)
Attributes which composed of several basic attributes are composite.
Address
Street
Address
Number
City
District
Street
Name
7. There are few requirements that we should consider in Good Database Design. Name two.
(3)
FAITHFULLNES:
• The design should be faithful to the specifications of the application. – That is, the entity sets
and their attributes should reflect reality.
• You can’t attach an attribute number-of-cylinders to Stars although that attribute could make
sense for an entity set Automobiles.
AVOIDING REDUNDANCY
• Everything one only -Two representations of the same thing take more space, when the data is
stored, than either representation alone
Whatever can go wrong will go wrong.
forget to update all available copies will cause problems.
SIMIPLICITY COUNTS
Avoid introducing more elements into your design than is absolutely NOT necessary
CHOOSING THE RIGHT RELATIONSHIPS
• Entity sets can be connected in various ways by relationships. However, adding to our design
every possible relationship is not often a good idea because:it can lead to redundancy
the resulting database could require much
more space to store redundant elements
and modifying the database could become too
complex.
8. Explain with an example what Database Integrity mean to you. (2).
Database integrity ensures that data entered into the database is accurate, valid, and consistent. Any
applicable integrity constraints and data validation rules must be satisfied before permitting a change
to the database.
Three basic types of database integrity constraints are:

Entity integrity, not allowing multiple rows to have the same identity within a table.

Domain integrity, restricting data to predefined data types, e.g.: dates.
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
Referential integrity, requiring the existence of a related row in another table, e.g. a customer
for a given customer ID.
9. Define Primary Key Attributes with an example (2)
Keys
are attributes or sets of attributes that uniquely identify an entity within its entity set.
Gives you unique access to a record in a table
Eg. Student (Student ID, FName, LName, DOB, PhoneNo, Gender, Village,)
10. What is Weak Entity Sets? (1)
A weak entity type has partial key which is the set of attributes that can identify weak entities that
belongs to the same parent (owner) entity. In the example not two dependents of the same employee
have the same name so that
DependentName becomes the partial key.
An entity type that does not have a primary key of it own
Consider the entity type DEPENDENT which is related to EMPLOYEE
DEPENDENT (DependentName, Birth Date, Sex, Relationship)
11. Outline with example the process of Normalization up to 3 normal form.(3)
(Exclude as we have not covered this topics)…bonus marks.
12. Give 2 operational benefits of having special Data Entry Forms. (2)
Control data collection and Entry
User Friendly
Promote Accuracy
No technology is capable of recognizing data characters as well as the human eye. In fact, "accuracy"
rates in the data conversion business are typically determined by comparing the results of a
conversion process with a visual examination of the source documents.
Simply put, the most accurate data detection device is the human eye. Consequently, keying is the
ideal form of data entry.
Keying provides assurance that your data is reliable because you can specify a guaranteed accuracy
level for your information. The accuracy of information becomes increasingly important as the size
and volume of information resources increases.
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13. Describe with example the concept Faithfullness Constraints. (2)
FAITHFULLNES:
• The design should be faithful to the specifications of the application. – That is, the entity sets
and their attributes should reflect reality.
• You can’t attach an attribute number-of-cylinders to Stars although that attribute could make
sense for an entity set Automobiles.
14. Identify and describe the three database anomalies. Give examples to back your
explanations. (3)
Database anomalies are the problems in relations that occur due to redundancy in the relations.
These anomalies affect the process of inserting, deleting and modifying data in the relations. Some
important data may be lost if a relations is updated that contains database anomalies. It is important
to remove these anomalies in order to perform different processing on the relations without any
problem.
Types of Anomalies.
Different types of database anomalies are as follows:
Insertion Anomaly.The insertion anomaly occurs when a new record is inserted in the relation. In this
anomaly, the user cannot insert a fact about an entity until he has an additional fact about another
entity.
Deletion Anomaly.The deletion anomaly occurs when a record is deleted from the relation. In this
anomaly, the deletion of facts about an entity automatically deleted the fact of another entity.
Modification Anomaly. The modification anomaly occurs when the record is updated in the relation. In
this anomaly, the modification in the value of specific attribute requires modification in all records in
which that value occurs.
Database anomalies, are really just unmatched or missing information caused by limitations or flaws
within a given database. Databases are designed to collect data and sort or present it in specific
ways to the end user. Entering or deleting information, be it an update or a new record can cause
issues if the database is limited or has ‘bugs’.
Modification anomalies or Update anomalies are data inconsistencies that resulted from data
redundancy or partial update. The Problems resulting from data redundancy in database table are
known as update anomalies. If a modification is not carried out on all the relevant rows, the database
will become inconsistent. So any database insertion, deletion or modification that leaves the database
in an inconsistent state is said to have caused an update anomaly.
Insertion anomalies are issues that come about when you are inserting information into the database
for the first time. To insert the information into the table, we must enter the correct details so that they
are consistent with the values for the other rows. Missing or incorrectly formatted entries are two of
the more common insertion errors. Most developers acknowledge that this will happen and build in
error codes that tell you exactly what went wrong.
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Deletion anomalies are obviously about issues with data being deleted, either when attempting to
delete and being stopped by an error or by the unseen drop off of data. If we delete a row from the
table that represents the last piece of data, the details about that piece are also lost from the
Database. These are the least likely to be caught or to stop you from proceeding. Because many
deletion errors go unnoticed for extended periods of time, they could be the most costly in terms of
recovery.
Database anomalies are a fact; we will all face them in one form or another in life. The importance of
backing up, storing offsite and data consistency checks come into full focus when you consider what
could be lost.
End of Test
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