You can schedule to take Oracle certification exams with Pearson Vue in effectively any order you care to. Oracle University will not stop you from taking the exams or penalize you in any way. For an example, consider the Oracle Database 11g Administrator Certified Professional credential. The full track consists of three exams and a hands-on training requirement. The most common sequence that certification candidates fulfill the requirements in is:
- Pass 1Z0-051 -- SQL Fundamentals I
- Pass 1Z0-052 --Administration I
- Take the hands-on training course
- Pass 1Z0-053 -- Administration II
However, there is absolutely nothing preventing a candidate from reversing that order entirely:
- Pass 1Z0-053 -- Administration II
- Take the hands-on training course
- Pass 1Z0-052 --Administration I
- Pass 1Z0-051 -- SQL Fundamentals I
In fact, you could pick any order and Oracle University won't miss a beat. Either path will lead to the 11g Administrator Certified Associate and 11g Administrator Certified Professional credentials. That said, there are definite advantages to the testing candidate for the more common sequence.
Probably the most compelling advantage is that the first sequence will provide testing candidates with the OCA certification after step two. Candidates won't receive the OCA certification in the second sequence until step four (they will simultaneously complete the OCA and OCP requirements).
A second consideration is that the 1Z0-051 exam is generally considered to be one of the easiest. The fact that it is unproctored and can be taken online means that testing candidates new to Oracle can use it to become familiar with Oracle certification exams before moving on to more complicated topics.
Finally, some candidates want to pass all three exams first and take the hands-on training afterward. While this is perfectly legitimate -- it means that anything you learn from the training is too late to apply towards passing the test. Unless you know the material in all three exams really well, it makes sense to take a training course that can improve your chances of passing and then schedule the exam. You will not receive the certification until all four steps have been completed.
Ultimately, you need to take the exams in the order that makes sense for your circumstances. If something makes it advisable to take an exam before one of the others, then do so. For example, maybe you receive a voucher for 1Z0-052 before you have taken 1Z0-051. If so -- do not be concerned that you are taking the exams 'out of order'. Once you have fulfilled all of the requirements for a given track, Oracle University will grant you the certification.
