You may take one copy of the book draft for personal use but not for distribution. Please do not post the draft on other web sites, instead, please put a link to this site. Alice's book Individual Chapters Table of Contents Chapter 1 - Database Systems Chapter 2 - Theoretical Background Chapter 3 - The Relational Model Chapter 4 - Conjunctive Queries Chapter 5 - Adding Negation: Algebra and Calcul