Add Record to DB and Return Auto_Increment ID?

Hi. I'm creating a class mapped to the functions of a guestbook. Each guestbook submission becomes an entry in a db table. I am using the DB Pear class. I'm new to PHP and my question is this: What is the best way to create a method that adds a new guestbook entry and returns its auto_increment id. I could use an "Insert" statement and then a "Select" statement to find out what id was added for the record, but that seems a little inefficient. Any ideas? Thanks for any help. Much appreciated, Brett