books.google.com - Understanding SQL's underlying theory is the best way to guarantee that your SQL code is correct and your database schema is robust and maintainable. On the other hand, if you're not well versed in the theory, you can fall into several traps. In SQL and Relational Theory, author C.J. Date demonstrates...http://books.google.com/books/about/SQL_and_Relational_Theory.html?id=406_pJtiJ6sC&utm_source=gb-gplus-shareSQL and Relational Theory
