This is an extraordinarily academic book. In his preface, C.J. Date goes so far as to lament having to use Structured Query Language (SQL) in some of his examples because it's "so far from being a true embodiment of relational principles." What's more, he writes in a very academic style, peppering his heavily footnoted prose with mathematical expressions and words like relevar and tuple. The academic style and highbrow language isn't a bad thing, since this book deals with complicated, largely abstract phenomena in depth.
Be aware that An Introduction to Database Systems is a far cry from the highly graphical, problem-focused books that target the community of commercial database developers, and as such requires more careful study. This book is about theories, concepts, and ideals rather than problems, solutions, and specific implementations. Per se, it will enable you to become a better database programmer--but only if you supplement it with practical guides and hands-on experience. --David Wall