Database Systems A Practical Approach to Design, Implementation, and Management, Connolly - Downloadable Solutions Manual (Revised)

SOLUTIONS TO REVIEW QUESTIONS



AND EXERCISES



FOR PART 1 – BACKGROUND (CHAPTERS 1 – 3)

, Solutions to Review Questions and Exercises




Chapter 1 Introduction to Databases ................................................................................................................ 3


Chapter 2 Database Environment....................................................................................................................... 7


Chapter 3 Database Architectures and the Web ....................................................................................... 11

,Chapter 1 Introduction to Databases

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;

• An organization maintaining all sales order information.



1.2 Discuss each of the following terms:



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

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 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 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 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 disadvantages of this approach.



Focus was on applications for which programs would be written, and all the data
required would 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.



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.



1.6 Discuss the roles of the following personnel in the database environment:



Data Administrator See Section 1.4.1