Understand the basic theory of SQL is the best way to ensure that the SQL code is correct and your database schema is robust and maintained. Date shows how you can apply relational theory directly to the use of SQL. With numerous examples and clear explanations about the reasons behind them, you'll learn how to deal with common SQL dilemma, such as: Should be given access to the database through views rather than base tables? SQL support "ratio is calculated," but they are better avoided. The constraints that are very important, but most SQL products do not support them properly. Database theory and practice have evolved since Edgar Codd originally defined the relational model back in 1969. Independent of each product SQL, SQL and Relational Theory draws on decades of research to present up-to-date treatment of the majority of the material available anywhere.