Alex: My deep gratitude goes to my wife, Liana, for helping me to organize material and make sure that examples in this book work as we say they should. I also thank Liana for putting up with my insane schedules.

Boris: I sincerely thank my wife, Kate, for her professional help, moral support, and unconditional understanding. Writing a book was a stressful process for both authors and their families. Kate not only helped me to go through these difficult times, but she also actively participated in the writing of this book by reviewing the chapters, helping with SQL examples, and making valuable suggestions and comments.

I am grateful to all my friends who were with me when I needed them.

My gratitude also goes to Professor Jaideep Srivastava, who introduced me to the relational database world.

Alex and Boris: Thanks to Jim Minatel, Senior Acquisitions Editor at Wiley Publishing, for his help with the project and his guidance through the maze of editorial procedures.

We thank the Wiley editorial team, especially Eric Newman and Maarten Reilingh, for helping to make this book better than it would otherwise have been, providing valuable suggestions on how to improve the book's content, and pointing out omissions, oversights, and outright bloopers.

Finally, we thank our technical editors for their help with preparing the publication.