I am working as a developer for 3 years and I am thinking of switch to dba.

I do not own any certificate nor received any training regarding the daily job of dba. My company also do not offer any chance of work/training related to a dba.

If I want to be a dba ( because of the salary and a much stable job than developer ), should I go to get some oracle certificates? I've also heard that you can't be a good dba if you cannot get a good understanding about the working OS such as windows/unix ( and to do that you also need to get some certificate on windows administration or unix administration ) but they recommend book of Rich Stevens over certificate.

I am confused on what should I do to make this happen.