The system has evolved from the file system, through a database system, with the advent of the Management Information System (MIS) and? Therefore, a dramatic increase in the amount of resources put into the field of re-engineering. Reengineering involves the redesign of an existing Information System, while utilizing the existing system as much as possible. This text takes a practical approach to re-engineering existing systems and look at data integration, and focus on proven methods and tools to: conversion of hierarchical or network database systems into relational database technology, or from a relational database and XML integration object-oriented database systems and expert systems to produce MIS and EIS systems Taking a very practical approach, this book describes in detail database conversion techniques, reverse engineering and forward engineering, and re-engineering methodology for information systems, offering a systematic software engineering approach for reusing existing database systems are built with technology "old", Many examples, illustrations and case studies are used, making the methodology easy to follow, and the CD is included containing solutions to the problem. This book is used for textbooks freshman undergraduate and postgraduate courses, and also for a professional reference book computer. Instructor's Guide available on the website: www.springer.com for lecturers, and help desk to use the CD-ROM available at the website: www.udw.com.hk / helpdesk.