What are some good books about databases?Database System Concepts is the book we used in the first database class at Caltech. The first several chapters focus on describing relational algebra and developing a solid foundation for the next several to build on as they introduce SQL and discuss the kinds of tradeoffs you might make in schema design and query optimization.
It's a solid intro text in that if you approach it without any prior database knowledge and stick with it, by the end you'll not only know syntactically how to define a schema and write complex queries, you'll also have a good mental framework for normalizing your schemas, optimizing queries, and defining the right indices. That said, it is a bit denser than other intro texts, and it will take you a bit longer to get to actually working with a real database, as the first several chapters stick strictly to operations in relational algebra. This book is certainly not perfect, but it's far better than any other intro relational database text that I've come across.