Because databases often stay in production for decades, careful design is critical to making the database serve the needs of your users over years, and to avoid subtle errors or performance problems. In this book, CJ Date, a leading exponent of relational databases, lays out the principles of good database design. Database Design and Relational Theory investigates denormalization, implicit dependencies, redundancy, and many other topics. DBAs will produce better designs and keep their data centers running better through the ideas conveyed in this book. Questions that this book answers include: What is Heath's Theorem, and why is it important? What is The Principle of Orthogonal Design? What makes some JDs reducible and others irreducible? What is dependency preservation, and why is it important? Should data redundancy always be avoided? Can it be?