I am a bit wonder on the sample test. Its subscription fee is quite high, however, there are only 100 questions in the pool. Moreover, 1z0-042 does not release yet, even if they took the beta exam 1z1-042, there should be 170+ questions, how similar the questions to the real thing is still one of my concerns.
In addition, they also provide 1z1-043 questions, however, the exam is even NOT in beta status.
My advice would be to look for sample questions to the 9i SQL (#1Z0-007) and 9i Administration I (#1Z0-031) tests, then sign-up to take the 10g (#1Z0-042) test. The differences between 9i and 10g are small and there's definitely a cost benefit between two tests (~$250+) to one test (~$125+).
There's an abundance of free questions for 8i and 9i, and many of the basic concepts have not changed (notable exceptions is OMF).
The differences between 9i and 10g are small and there's definitely a cost benefit between two tests (~$250+) to one test (~$125+).
In addition to the cost difference, 10g provides more new features in the questions, such as Flashback query and transaction, Recycle bin, Enhanced Block Recovery, etc. You might find the questions a bit more chanllenging than 9i.
IMHO, these are more than enough to take care of SQL and PL/SQL exams. I like Oracle Concepts a lot, it gives you an overall Oracle database architecture. I admit this is a poor boy way to prepare for the exam - you have to map the objectives to the document. I only skimmed through the objectives and document, in case I miss something, here is Oracle9i Database List of Books