Database technology is an important subject in Computer Science. Every large company and nation needs a database to store information. The technology has evolved from file systems in the 60s to Hierarchical and Network databases in the 70s to relational databases in the 80s objectoriented databases in the 90s and to XML documents and NoSQL today. As a result there is a need to reengineer and update old databases into new databases. This book presents solutions for this task. In this fourth edit