Why I Wrote This Book

Queries, queries, queries. My goal from the beginning of this project has not been so much to write a "SQL Cookbook" as to write a "Query Cookbook." I've aimed to create a book comprised of queries ranging from the relatively easy to the relatively difficult in hopes the reader will grasp the techniques behind those queries and use them to solve his own particular business problems. I hope to pass on many of the SQL programming techniques I've used in my career so that you, the reader, will take them, learn from them, and eventually improve upon them; through this cycle we all benefit. Being able to retrieve data from a database seems so simple, yet in the world of Information Technology (IT) it's crucial that the operation of data retrieval be done as efficiently as possible. Techniques for efficient data retrieval should be shared so that we can all be efficient and help each other improve.

Consider for a moment the outstanding contribution to mathematics by Georg Cantor, who was the first to realize the vast benefit of studying sets of elements (studying the set itself rather than its constituents). At first, Cantor's work wasn't accepted by many of his peers. In time, though, it was not only accepted, but set theory is now considered the foundation of mathematics! More importantly, however, it was not through Cantor's work alone that set theory became what it is today; rather, by sharing his ideas, others such as Ernst Zermelo, Gottlob Frege, Abraham Fraenkel, Thoralf Skolem, Kurt Gödel, and John von Neumann developed and improved the theory. Such sharing not only provided everyone with a better understanding of the theory, it made for a better set theory than was first conceived.