If you write programs to run against an Oracle database, you spend a lot of time and mental energy writing queries to return the data your programs need. Knowledge of SQL, and particularly of Oracle's implementation of SQL, is the key to writing good queries in a timely manner. In this book, the authors share their knowledge of Oracle SQL, and show you many creative techniques that you can use to advantage in your own applications. This book shows you how to: leverage Oracle's vast library of built-in SQL functions; query time-based data, and write joins involving date and time ranges; use Oracle SQL's hierarchical query features to deal with data best represented in a tree format; use DECODE and CASE to implement conditional logic in your queries; use Oracle's new, analytic SQL features to write ranking queries, lag and lead queries, and windowing queries; and join data from two or more tables using the newly supported SQL92 join syntax. In addition, you'll see how SQL can best be integrated with PL/SQL. You'll also learn various best practices to help you write SQL queries that perform efficiently.