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SOLUTIONS TO REVIEW QUESTIONS
U
AND EXERCISES
R
FOR PART 1 – BACKGROUND (CHAPTERS 1 – 3)
SE
D
O
C
ALL CHAPTERS INCLUDED
S
ALL ANSWERS INCLUDED
,Database Systems: Instructor’s Guide - Part III All Chapters ⬛⬛
⬛
Chapter 1 Introduction to Databases
All Answers ⬛⬛⬛
Review Questions
1.1 List four examples of database systems other than those listed in Section 1.1.
Some examples could be:
• A system that maintains component part details for a car manufacturer;
• An advertising company keeping details of all clients and adverts placed with them;
• A training company keeping course information and participants’ details;
•
N
An organization maintaining all sales order information.
1.2 Discuss each of the following terms:
U
Data For end users, this constitutes all the different values connected with the
various objects/entities that are of concern to them. See also Section 1.3.4.
Database See Section 1.3.1
R
Database Management System See Section 1.3.2
Database Application Program See Section 1.3.3
Data Independence This is essentially the separation of underlying file structures from the
SE
programs that operate on them, also called program-data independence. See
also Sections 1.2.2 and 1.3.1.
Security The protection of the database from unauthorized users, which may involve
passwords and access restrictions. See also Section 1.6.
Integrity The maintenance of the validity and consistency of the database by use of
D
particular constraints that are applied to the data. See also Section 1.6.
Views These present only a subset of the database that is of particular interest to a
user. Views can be customized, for example, field names may change, and
O
they also provide a level of security preventing users from seeing certain
data. See also Section 1.3.3.
1.3 Describe the approach taken to the handling of data in the early file-based systems. Discuss the
C
disadvantages of this approach.
Focus was on applications for which programs would be written, and all the data required would
S
be stored in a file or files owned by the programs. See also Section 1.2.
Clearly, each program was responsible for only its own data, which could be repeated in other
program’s data files. Different programs could be written in different languages, and would not be
able to access another program’s files. This would be true even for those programs written in the
same language, because a program needs to know the file structure before it can access it. See also
Section 1.2.2.
1.4 Describe the main characteristics of the database approach and contrast it with the file-based
approach.
2
,Database Systems: Instructor’s Guide - Part III
Focus is now on the data first, and then the applications. The structure of the data is now kept
separate from the programs that operate on the data. This is held in the system catalog or data
dictionary. Programs can now share data, which is no longer fragmented. There is also a reduction
in redundancy, and achievement of program-data independence. See also Section 1.3.
1.5 Describe the five components of the DBMS environment and discuss how they relate to each
other.
See Section 1.3.3.
N
1.6 Discuss the roles of the following personnel in the database environment:
Data Administrator See Section 1.4.1
Database Administrator See Section 1.4.1
U
Logical Database Designer See Section 1.4.2
Physical Database Designer See Section 1.4.2
Application Developer See Section 1.4.3
R
End-Users See Section 1.4.4
1.7 Discuss the three generations of DBMSs.
SE
The CODASYL and hierarchical approaches represented the first generation of DBMSs. They
were based on the concept that smaller components come together as parts of larger
components, and so on, until the final product is assembled. This structure, which conforms to
an upside-down tree, is also known as a hierarchical structure.
D
Relational DBMSs are referred to as second-generation DBMSs. In 1970, E. F. Codd of the
IBM Research Laboratory produced his highly influential paper on the relational data model
(“A relational model of data for large shared data banks,” Codd, 1970). This paper was very
O
timely and addressed the disadvantages of the former approaches. Many experimental
relational DBMSs were implemented thereafter.
C
In response to the increasing complexity of database applications, two “new” systems have
emerged: the object-oriented DBMS (OODBMS) and the object-relational DBMS
(ORDBMS). However, unlike previous models, the actual composition of these models is not
S
clear. This evolution represents third generation DBMSs.
1.8 Discuss the advantages and disadvantages of database management systems.
See Section 1.6
3
, Database Systems: Instructor’s Guide - Part III
Exercises
1.9 Interview some users of database systems. Which DBMS features do they find most useful and
why? Which DBMS facilities do they find least useful and why? What do these users perceive to
be the advantages and disadvantages of the DBMS?
Select a variety of users for a particular DBMS. If the users are using different DBMSs, group the
answers for the different systems, which will give an overall picture of specific systems.
1.10 Write a small program (using pseudocode, if necessary) that allows entry and display of client
details including a client number, name, address, telephone number, preferred number of rooms,
N
and maximum rent. The details should be stored in a file. Enter a few records and display the
details. Now repeat this process but rather than writing a special program, use any DBMS that
you have access to. What can you conclude from these two approaches?
U
The program can be written in any appropriate programming language, such as Pascal,
FORTRAN, C. It should adhere to basic software engineering principles including being well-
structured, modular, and suitably commented. It is important to appreciate the process involved
R
even in developing a small program such as this. The DBMS facilities to structure, store, and
retrieve data are used to the same effect. The differences in the approaches, such as the effort
involved, potential for extension, ability to share the data should be noted.
SE
1.11 Study the DreamHome case study presented in Section 10.4 and Appendix A. In what ways would
a DBMS help this organization? What data can you identify that needs to be represented in the
database? What relationships exist between the data? What queries do you think are required?
D
It may be useful to review the file-based approach and the database approach here before tackling
the first part of the exercise. Careful reading and thinking about how people might use the
applications should help in carrying out the rest of the exercise.
O
1.12 Study the Wellmeadows Hospital case study presented in Appendix B.3. In what ways would a
DBMS help this organization? What data can you identify that needs to be represented in the
database? What relationships exist between the data?
C
The approach used for Exercise 1.10 should be used for this exercise also.
S
1.13 Discuss what you consider to be the three most important advantages for the use of a DBMS for a
company like DreamHome and provide a justification for your selection. Discuss what you
consider to be the three most important disadvantages for the use of a DBMS for a company like
DreamHome and provide a justification for your selection.
Students should review section 1.6 to make a list of advantages and disadvantages of using a
DBMS.
1.14 Using any Web browser, look at some of the following Web pages and discover the wealth of
information available there:
4
SOLUTIONS TO REVIEW QUESTIONS
U
AND EXERCISES
R
FOR PART 1 – BACKGROUND (CHAPTERS 1 – 3)
SE
D
O
C
ALL CHAPTERS INCLUDED
S
ALL ANSWERS INCLUDED
,Database Systems: Instructor’s Guide - Part III All Chapters ⬛⬛
⬛
Chapter 1 Introduction to Databases
All Answers ⬛⬛⬛
Review Questions
1.1 List four examples of database systems other than those listed in Section 1.1.
Some examples could be:
• A system that maintains component part details for a car manufacturer;
• An advertising company keeping details of all clients and adverts placed with them;
• A training company keeping course information and participants’ details;
•
N
An organization maintaining all sales order information.
1.2 Discuss each of the following terms:
U
Data For end users, this constitutes all the different values connected with the
various objects/entities that are of concern to them. See also Section 1.3.4.
Database See Section 1.3.1
R
Database Management System See Section 1.3.2
Database Application Program See Section 1.3.3
Data Independence This is essentially the separation of underlying file structures from the
SE
programs that operate on them, also called program-data independence. See
also Sections 1.2.2 and 1.3.1.
Security The protection of the database from unauthorized users, which may involve
passwords and access restrictions. See also Section 1.6.
Integrity The maintenance of the validity and consistency of the database by use of
D
particular constraints that are applied to the data. See also Section 1.6.
Views These present only a subset of the database that is of particular interest to a
user. Views can be customized, for example, field names may change, and
O
they also provide a level of security preventing users from seeing certain
data. See also Section 1.3.3.
1.3 Describe the approach taken to the handling of data in the early file-based systems. Discuss the
C
disadvantages of this approach.
Focus was on applications for which programs would be written, and all the data required would
S
be stored in a file or files owned by the programs. See also Section 1.2.
Clearly, each program was responsible for only its own data, which could be repeated in other
program’s data files. Different programs could be written in different languages, and would not be
able to access another program’s files. This would be true even for those programs written in the
same language, because a program needs to know the file structure before it can access it. See also
Section 1.2.2.
1.4 Describe the main characteristics of the database approach and contrast it with the file-based
approach.
2
,Database Systems: Instructor’s Guide - Part III
Focus is now on the data first, and then the applications. The structure of the data is now kept
separate from the programs that operate on the data. This is held in the system catalog or data
dictionary. Programs can now share data, which is no longer fragmented. There is also a reduction
in redundancy, and achievement of program-data independence. See also Section 1.3.
1.5 Describe the five components of the DBMS environment and discuss how they relate to each
other.
See Section 1.3.3.
N
1.6 Discuss the roles of the following personnel in the database environment:
Data Administrator See Section 1.4.1
Database Administrator See Section 1.4.1
U
Logical Database Designer See Section 1.4.2
Physical Database Designer See Section 1.4.2
Application Developer See Section 1.4.3
R
End-Users See Section 1.4.4
1.7 Discuss the three generations of DBMSs.
SE
The CODASYL and hierarchical approaches represented the first generation of DBMSs. They
were based on the concept that smaller components come together as parts of larger
components, and so on, until the final product is assembled. This structure, which conforms to
an upside-down tree, is also known as a hierarchical structure.
D
Relational DBMSs are referred to as second-generation DBMSs. In 1970, E. F. Codd of the
IBM Research Laboratory produced his highly influential paper on the relational data model
(“A relational model of data for large shared data banks,” Codd, 1970). This paper was very
O
timely and addressed the disadvantages of the former approaches. Many experimental
relational DBMSs were implemented thereafter.
C
In response to the increasing complexity of database applications, two “new” systems have
emerged: the object-oriented DBMS (OODBMS) and the object-relational DBMS
(ORDBMS). However, unlike previous models, the actual composition of these models is not
S
clear. This evolution represents third generation DBMSs.
1.8 Discuss the advantages and disadvantages of database management systems.
See Section 1.6
3
, Database Systems: Instructor’s Guide - Part III
Exercises
1.9 Interview some users of database systems. Which DBMS features do they find most useful and
why? Which DBMS facilities do they find least useful and why? What do these users perceive to
be the advantages and disadvantages of the DBMS?
Select a variety of users for a particular DBMS. If the users are using different DBMSs, group the
answers for the different systems, which will give an overall picture of specific systems.
1.10 Write a small program (using pseudocode, if necessary) that allows entry and display of client
details including a client number, name, address, telephone number, preferred number of rooms,
N
and maximum rent. The details should be stored in a file. Enter a few records and display the
details. Now repeat this process but rather than writing a special program, use any DBMS that
you have access to. What can you conclude from these two approaches?
U
The program can be written in any appropriate programming language, such as Pascal,
FORTRAN, C. It should adhere to basic software engineering principles including being well-
structured, modular, and suitably commented. It is important to appreciate the process involved
R
even in developing a small program such as this. The DBMS facilities to structure, store, and
retrieve data are used to the same effect. The differences in the approaches, such as the effort
involved, potential for extension, ability to share the data should be noted.
SE
1.11 Study the DreamHome case study presented in Section 10.4 and Appendix A. In what ways would
a DBMS help this organization? What data can you identify that needs to be represented in the
database? What relationships exist between the data? What queries do you think are required?
D
It may be useful to review the file-based approach and the database approach here before tackling
the first part of the exercise. Careful reading and thinking about how people might use the
applications should help in carrying out the rest of the exercise.
O
1.12 Study the Wellmeadows Hospital case study presented in Appendix B.3. In what ways would a
DBMS help this organization? What data can you identify that needs to be represented in the
database? What relationships exist between the data?
C
The approach used for Exercise 1.10 should be used for this exercise also.
S
1.13 Discuss what you consider to be the three most important advantages for the use of a DBMS for a
company like DreamHome and provide a justification for your selection. Discuss what you
consider to be the three most important disadvantages for the use of a DBMS for a company like
DreamHome and provide a justification for your selection.
Students should review section 1.6 to make a list of advantages and disadvantages of using a
DBMS.
1.14 Using any Web browser, look at some of the following Web pages and discover the wealth of
information available there:
4
