Although I haven't taken the OCP exam yet, I have been using this book (which I got with the OCP Oracle9i DBA Certification Boxed Set) as a reference during my training. Since the classes are compressed and fast this book has cleared up a lot of information that was only touched upon by my instructor.Since I have not taken the exam I cannot predict how useful this book is for preparation; however, it gives clear information and has more than once allowed me to understand concepts that I was unable to get in class.Note: there are editing flaws and inconsistent writing that do make this book ponderous at times. There have been times when I wished the authors and editors had paid more attention to the book, and other times when I silently thanked them for clarifying a concept.