By Alexis Leon & Mathews Leon, Leon Vikas, 2002.
During the Machine Age, the measure of power
was heavy iron typified by cannon, locomotives and rolling mills.
In the Information Age, the measure of power is the depth,
timeliness and accessibility of knowledge. Communication bandwidth
has become more crucial than shop floor capacity. Without the
ability to communicate by telephone, e-mail or fax an organization
is deaf and dumb. Without access to the database, an organization
is blind. Because every firm is now directly or indirectly reliant
on computer software, every decision point in the enterprise is an
interface point between workers and information systems. The
alignment of the information flows with workflows distributed
throughout an organization is known as enterprise computing.
In an information-intensive business
environment, knowledge is power. Competitiveness pivots on how
effectively information systems enable management and staff to
gain advantages. The single most important requirement for
commercial power is the ability to transform operational data into
tactical information, and ultimately into strategic knowledge. The
main resource that fuels this power is the corporate database.
This book introduces the fundamental concepts
necessary for designing, using and implementing database systems
and applications. This book assumes no previous knowledge of
databases or database technology and the concepts are built from
grounds-up-from the basic concepts to the advanced techniques and
technologies. The book is self-contained and has a flexible
organization to suit the needs of individual courses.
This book is meant to be used as a textbook in
database systems at the undergraduate, graduate or postgraduate
level (B.Sc., BCA, BE, B.Tech., M.Sc., MCA, ME, M. Tech., etc.)
and as a reference book.
A question that might reasonably greet the
appearance of yet another book on Database Systems is, does the
world really need one more? Presumably every author writing on a
well-covered topic believes he or she has something different to
contribute, and we are no exception. Many of the books available
on this subject are nothing short of excellent and most of them
delve into topics and levels of analysis not addressed in this
Some of the books cover the topics in great
depth and detail while others cover only the most important topics
and that too in a very superficial manner. Obviously no single
book on this subject can meet everyone's needs, but many lie too
close to either end of the spectrum to be really helpful. At the
low end there are the superficial ones that leaves the readers
confused or unsatisfied. Those at the high end cover the subject
with such thoroughness as to be overwhelming.
Our goal when we started writing this book was
to produce a volume that will cover all the required topics to a
level that is not overwhelming but enough to satisfy the needs of
our target audience and present the material in a clear and
easy-to-understand style with real world examples and exercises.
In this book, we have tried to steer a middle
course between too little and too much, covering the necessary
topics in sufficient detail while avoiding an overly earnest one.
We have included a lot of pedagogical features like review
questions, exercises, case studies, solved examples, etc. Such a
hands-on approach is often the most effective way of getting the
knowledge to stick as it gives the reader a chance to reflect and
refresh what he or she has learned.
We have tried to make this book as interesting
and reader-friendly as possible. We have used an easy-to-read
writing style, with a lot bulleted lists, tables and illustrations
to make learning easy and enjoyable. We have also tried to explain
the monotonous and dry topics like relational algebra, relational
calculus, indexing, hashing, query processing, etc. in simple,
clear and easy-to-understand language.
At the end of each chapter, there are review
questions-descriptive, fill in the blanks, true or false and
multiple choice questions-to help the readers test their
knowledge. We have also included a list of books in each chapter
(selected bibliography), for the readers who want to learn more
about the topics covered in that chapter.