If anyone is interested, Steven Feuerstein runs a site called the PL/SQL challenge, which offers a daily quiz to improve your PL/SQL skills. I only raise this as a way of boasting that today's question is one that I wrote. It's quite possibly the nearest thing I've ever managed to fame on the internet.
For Oracle-related work, contact me through Linked-In.
For Oracle-related work, contact me through Linked-In.