As developers, we've created heuristics that help us build robust systems and employed test-driven development (TDD) to improve code design and counter instability. Yet object-oriented development principles and TDD have failed to gain traction in the database world. That’s because database development involves an additional driving force-the data. Max Guernsey shows how to treat databases as objects with classes of their own-rather than as containers of objects-and how to drive database designs from tests. He illustrates a way to give these database classes the ability to upgrade old data without introducing undue risk. Max also shares how to apply good object-oriented design principles to database classes and how to enforce semantic connections between databases and clients. Max demonstrates how it all works together, ensuring that your production databases work exactly the same as test databases, minimizing the risk of design changes, and enabling client applications to more easily keep up with database changes.