Book excerpt: This well-received book, now in its third edition, is a comprehensive presentation of the fundamentals of object-oriented database systems (OODBMS). It provides extensive coverage of the different approaches to object data management, including the three major approaches--semantic database systems approach, object-oriented programming language extension approach, and the relational extension approach--as well as the various types of architectures of object-oriented database systems. The book discusses all recent developments in this field, such as the emergence of Java as the dominant object-oriented programming language--resulting in upcoming OODBMS products such as Ozone--and the provision of object-oriented database features in object-relational database systems (ORDBMS) products such as Oracle 9i and DB2. The new edition provides an extensive discussion of PostgreSQL, a popular open source object-oriented database system which has emerged as a viable alternative to expensive commercial database systems such as Oracle. The book is extensively illustrated, which enables students to develop a firm grasp of the underlying concepts. The chapter-end exercises help in testing the students' comprehension of the fundamental principles. The book is primarily meant for students of IT-related programmes having courses in database systems. Computer professionals will also find the book immensely useful.