If you already have an 11g (or 10g ot 9i) OCA certification, then you can upgrade it. Requisites are shown here:
Select the "Upgrade" tab and then the OCA option
You need to attend 1 Oracle 12c course and take an additional exam. If you plan to do the OCA certification you need to take 2 exams.
Hope this helps
Just to clarify - If you've passed exam 1Z0-007, this exam is still valid to fulfill the SQL pre-requisite for 12c OCA. If you've passed 1Z0-007, you can go on to earn 12c DBA OCA by passing 1Z0-062.
Oracle Certification Program
thanks a lot to everyone for the help.