If you don't understand MySQL's EXPLAIN output, this webinar is for you. EXPLAIN output is confusing, but if you understand how it's created, it'll make sense to you.
You'll leave this webinar with the knowledge necessary to understand the most complex query plans, including those with filesorts, subqueries, and UNIONs. You'll see the internals of MySQL from a new angle. That knowledge will prepare you to reason about query execution plans the same way the MySQL server does. As a result, you'll be able to write queries that get the best performance from MySQL's query optimizer and executioner.