Adatabase-management system (DBMS)is a collection of interrelated data and
a set of programs to access those data. The collection of data, usually referred to
as thedatabase, contains information relevant to an enterprise. The primary goal
of aDBMSis to provide a way to store and retrieve database information that is
bothconvenientandefficient.
Database systems are designed to manage large bodies of information. Man-agement of data involves both defining structures for storage of information
and providing mechanisms for the manipulation of information. In addition, the
database system must ensure the safety of the information stored, despite system
crashes or attempts at unauthorized access. If data are to be shared among several
users, the system must avoid possible anomalous results.
Because information is so important in most organizations, computer scien-tists have developed a large body of concepts and techniques for managing data.
These concepts and techniques form the focus of this book. This chapter briefly
introduces the principles of database systems