Hi Hu
Answering you questions:
I used Oracle 8i � SQL & PL/SQL Exam Guide � Jason S. Couchman � ISBN 0072191538 . It is a very good source and it covers all certification objectives. Also it has valuable mock exams, tougher that the real ones. I am not sure, but I believe that PL-SQL did not change a lot, from version 8 to 9. I guess that probably only some new functions. Anyway, because it was written for the old version, probable now it is a bookstore bargain.
Mock tests from Whizlabs are great and they cover everything which is needed in higher level. Don�t use Boson, at least for PL-SQL certifications, because some of their questions are not related to exam topics at all.
AMERICO SOUZA<br />MSCS, BSCS and BSEE <br />ACHIEVEMENTS<br />CompTIA (A+), Cisco (CCNA), Oracle (OCA - PL/SQL), Sun (Java, J2EE and EJB).<br />Currently persuing Oracle's Forms Certification