“The book is aimed at an eclectic audience. Most broadly, it should be a useful resource for any computer scientist or mathematician who wishes to find out what database theory is about. Database researchers and practitioners should find it useful as a reference to both classical material and to advanced topics, otherwise scattered in sometimes hard-to-read papers. As a textbook, it is aimed at graduate students and seniors who would use the book as the main text in a database theory course or as complementary material in a database systems course. The book is fairly self-contained. Some needed background is provided concisely in the preliminaries, and the reader is told where more can be found.”