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I was honored to work with Chris Date to bring his legendary relational theory class to video and the web. During the making of this video Date shared a number of stories about his collaborations with Ted Codd. Date dedicates this video to Codd and his brilliant contributions to computer science. In this video, Date shows us how to write SQL code that's logically correct; how to avoid various SQL traps and pitfalls; and, more generally, how to use SQL as if it were a true relational language.
Here I've posted a sample first chapter of Date's three day course that reviews relational model basics and important properties of relations. It also introduces a crucial logical difference: viz., the difference between relation values and relation variables (relvars).
Date's meticulous attention to detail in preparing, delivering, and putting the final touches on this course was both humbling and exhilarating. His focus, eloquence and command of his curriculum inspires us to write accurate SQL code. Enjoy.
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. In SQL and Relational Theory, author C.J. Date demonstrates how you can apply relational theory directly to your use of SQL, with numerous examples and clear explanations of the reasoning behind them. Anyone with a modest to advanced background in SQL will benefit from the many insights in this book.
