ICT2641 EXAM
PACK 2023
,Companion CD-Rom resource: Answers to selected Questions and
Problems
, Answers to selected Questions and Problems
Database Systems: Design, Implementation and Management (International Edition) by Rob, Coronel & Crockett
Companion CD-Rom
Chapter 1, “Database Systems”
Answers to Selected Review Questions
1. Discuss each of the following terms:
a. data
Raw facts from which the required information is derived. Data have little meaning unless they are
grouped in a logical manner.
b. field
A character or a group of characters (numeric or alphanumeric) that describes a specific characteristic. A
field may define a telephone number, a date, or other specific characteristics that the end user wants to keep
track of.
c. record
A logically connected set of one or more fields that describes a person, place, event, or thing. For
example, a CUSTOMER record may be composed of the fields CUST_NUMBER, CUST_LNAME,
CUST_FNAME, CUST_INITIAL, CUST_ADDRESS, CUST_CITY, CUST_COUNTRY,
CUST_POSTCODE, CUST_AREACODE, and CUST_PHONE.
d. file
Historically, a collection of file folders, properly tagged and kept in a filing cabinet. Although such
manual files still exist, we more commonly think of a (computer) file as a collection of related records that
contain information of interest to the end user. For example, a sales organization is likely to keep a file
containing customer data. Keep in mind that the phrase related records reflects a relationship based on
function. For example, customer data are kept in a file named CUSTOMER. The records in this customer
2
, Answers to selected Questions and Problems
Database Systems: Design, Implementation and Management (International Edition) by Rob, Coronel & Crockett
Companion CD-Rom
file are related by the fact that they all pertain to customers. Similarly, a file named PRODUCT would
contain records that describe products – the records in this file are all related by the fact that they all pertain
to products. You would not expect to find customer data in a product file, or vice versa.
3. Discuss the lack of data independence in file systems.
File systems exhibit data dependence because file access is dependent on a file's data
characteristics. Therefore, any time the file data characteristics are changed, the programs that access
the data within those files must be modified. Data independence exists when changes in the data
characteristics don't require changes in the programs that access those data.
5. What is data independence, and why is it important?
Data independence exists when data access programs are not subject to change when any of the file's
data characteristics change. Data independence is important because it substantially decreases programming
effort and program maintenance costs.
7. What is the role of a DBMS, and what are its advantages?
A database management system (DBMS) is a collection of programs that manages the database structure
and controls access to the data stored in the database. Figure 1.2 (shown in the text) illustrates that the
DBMS serves as the intermediary between the user and the database. The DBMS receives all application
requests and translates them into the complex operations required to fulfill those requests. The DBMS hides
much of the database’s internal complexity from the application programs and users. The application
3
PACK 2023
,Companion CD-Rom resource: Answers to selected Questions and
Problems
, Answers to selected Questions and Problems
Database Systems: Design, Implementation and Management (International Edition) by Rob, Coronel & Crockett
Companion CD-Rom
Chapter 1, “Database Systems”
Answers to Selected Review Questions
1. Discuss each of the following terms:
a. data
Raw facts from which the required information is derived. Data have little meaning unless they are
grouped in a logical manner.
b. field
A character or a group of characters (numeric or alphanumeric) that describes a specific characteristic. A
field may define a telephone number, a date, or other specific characteristics that the end user wants to keep
track of.
c. record
A logically connected set of one or more fields that describes a person, place, event, or thing. For
example, a CUSTOMER record may be composed of the fields CUST_NUMBER, CUST_LNAME,
CUST_FNAME, CUST_INITIAL, CUST_ADDRESS, CUST_CITY, CUST_COUNTRY,
CUST_POSTCODE, CUST_AREACODE, and CUST_PHONE.
d. file
Historically, a collection of file folders, properly tagged and kept in a filing cabinet. Although such
manual files still exist, we more commonly think of a (computer) file as a collection of related records that
contain information of interest to the end user. For example, a sales organization is likely to keep a file
containing customer data. Keep in mind that the phrase related records reflects a relationship based on
function. For example, customer data are kept in a file named CUSTOMER. The records in this customer
2
, Answers to selected Questions and Problems
Database Systems: Design, Implementation and Management (International Edition) by Rob, Coronel & Crockett
Companion CD-Rom
file are related by the fact that they all pertain to customers. Similarly, a file named PRODUCT would
contain records that describe products – the records in this file are all related by the fact that they all pertain
to products. You would not expect to find customer data in a product file, or vice versa.
3. Discuss the lack of data independence in file systems.
File systems exhibit data dependence because file access is dependent on a file's data
characteristics. Therefore, any time the file data characteristics are changed, the programs that access
the data within those files must be modified. Data independence exists when changes in the data
characteristics don't require changes in the programs that access those data.
5. What is data independence, and why is it important?
Data independence exists when data access programs are not subject to change when any of the file's
data characteristics change. Data independence is important because it substantially decreases programming
effort and program maintenance costs.
7. What is the role of a DBMS, and what are its advantages?
A database management system (DBMS) is a collection of programs that manages the database structure
and controls access to the data stored in the database. Figure 1.2 (shown in the text) illustrates that the
DBMS serves as the intermediary between the user and the database. The DBMS receives all application
requests and translates them into the complex operations required to fulfill those requests. The DBMS hides
much of the database’s internal complexity from the application programs and users. The application
3
