How to get Oracle certification

I want to do certification in Oracle kindly tell me what are all the exams I need to take? Because there are some categories like pl/sql, sql, DBA… etc. But if I want to build my career in ORACLE then do I need to take all exams in all categories? This is the biggest question for me. Even I searched for an answer in OTN networks. But I did not get.I haven’t completed any certification yet. Please suggest … I am waiting for ur reply….