To answer your questions:

1) is it possible to study DBA/PHD in Business Administration "WITHOUT" a Master in Business Administration certificate?
-It is possible to study PhD without an MBA (but you must have really excellent degree result). For DBA, I have a friend who has a Master of Management before getting his DBA.

2) If yes, which University offers it and how?
- I know most public and private universities offer PhD (as long as you have first class honours in your bachelor degree, normally you just have to apply for PhD and depending on your research experience, the uni post grad center will advise you accordingly). However, for DBA I am not too sure. Also, the course fees for DBA will be more pricey compared to PhD.

3) Is it possible to complete PHD/DBA within 2 years?
- For PhD, it all depends on your commitment, discipline, determination, perseverance. You can finish it within 2 years. But for most of the universities I know, studying PhD on a full-time basis takes 3 years to complete. Dependent on the uni again, perhaps you can submit your thesis earlier..before the end of 3 years.

For DBA, there are some coursework/syllabus that you have to complete. It is not on a fully research basis. So probably you will need more than 2 years to complete it.