This week's book giveaway is in the Testing forum. We're giving away four copies of The Way of the Web Tester: A Beginner's Guide to Automating Tests and have Jonathan Rasmusson on-line! See this thread for details.
Calling first() allow you to move the cursor back to the ResultSet. This could be useful if you are using the same ResultSet somewhere else, and you want to reiterate from the start. If you don't, then you don't need to use first().