03
2002
Database Management Systems
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 book.
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.
