I have another book by CJ Date book but sometimes is too pedantic and
i loose the sight
(it's like reading Lord Of The Rings, you must have patience to read
this dialect )
Let's hope that this one is good , and i might kill some trees buying it
and The White Wizard can show us how to apply Relational theory to SQL

http://oreilly.com/catalog/9780596523060/

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, you'll learn how to deal with common SQL
dilemmas, such as:

* Should database access granted be through views instead of base tables?
* Nulls in your database are causing you to get wrong answers.
Why? What can you do about it?
* Could you write an SQL query to find employees who have never
been in the same department for more than six months at a time?
* SQL supports "quantified comparisons," but they're better
avoided. Why? How do you avoid them?
* Constraints are crucially important, but most SQL products don't
support them properly. What can you do to resolve this situation?


--
developer flamerobin.org