Oracle: Run a SQL execution plan report

Oracle: Compare SQL subqueries

Oracle: custom SQL report

Oracle: SQL optimization techniques

Understanding SQL execution

Oracle hash joins

Oracle SQL all_rows, first_rows, rule

Oracle Optimizer Plan Stability

Oracle: Viewing SQL execution plans

SQL query re-formulation

Oracle SQL Quiz

Analyzing a schema for cost-based SQL optimization

Examine different optimizer modes

Writing efficient SQL

SQL Tuning with temporary tables

Oracle Materialized Views

Oracle Enabling Materialized Views

Create Oracle indexes

Oracle Extensions to the SQL Language

Understanding SQL built-in functions

Oracle Using decode and case functions

Oracle Basic Aggregation functions max min sum avg

Oracle Analytical SQL functions - rollup - cube

Oracle Using the SQL GROUPING function

Oracle Aggregation and in-line views

Oracle UNIX Consulting

Oracle Use a CASE statement in SQL

Oracle Create a custom SQL BIF

Oracle Create an abstract data type

Oracle Database PL/SQL Program Constructs

For a complete overview of Oracle SQL, see the book "Easy Oracle SQL".  It's only $9.95 and has a downloadable code depot: http://www.rampant-books.com/book_2005_1_easy_sql.htm