Oracle/DB

Oracle Certification has two main role, one is Oracle DBA and another is Oracle Developer. In Oracle DBA, one need to know Oracle SQL or Oracle Administration. To become Oracle Developer, one need to be Masters in Oracle SQL or Oracle PL/ SQL. Oracle has three main level of certification OCA, OCP and OCM.
OCA stands for Oracle Certified Associate. For joining this level, OCA aspirant has to appear in an exam called Oracle SQL Fundamental and another exam i.e. Oracle Database Administration 1. After completing these two exam, aspirant get the OCA Certificate.
OCP stands for Oracle Certificate Profession. To get the certificate of OCP, aspirant must have a title of OCA. If a student has the title of OCA, then aspirant has to appear in the exam Oracle Database Administration2. After passing this exam, student has to take training in any topics decided by Oracle.
Finally, one is OCM and it stands for Oracle Certificate Master. This level is only for student who has OCP Title. This is a practical exam of 48 hour in which student has to resolve problem on real-time server and for every task, there is a fixed time to solve.

Hello,
Oracle is a database program. This course is one of the most interesting and challenging course in the database domain. It may or may not be included as a part of the syllabus of degree courses in computers. The best option is to study this course via a certification program provided by any computer training institute. Such institutes provide their own certifications. Recommending an institute for this course is a difficult job as there are a bunch of them in any city or in a metropolitan or cosmopolitan city nearest to the student's residence. Some of these might be popular, some might not be. Some could have a well-built infrastructure, others might not. The key idea is to find a good mentor who can help a student understand the fundamentals of the subject and make the student capable of finding solution to problems.
These institutes design the syllabus of Oracle as per their convenience and areas of expertise. However, to gain complete knowledge of the subject, it is recommended to option for a course certified by Oracle. The syllabuses for these courses are designed by Oracle and cannot be modified by any institute. On completion, the certificates are provided by Oracle, and not by any institute. These courses can be pursued via online self-study or via any Oracle - authorized Institute.

Hi Srinivas,
Mentioned all three are in a good demand in their own field but the common factor is Skill, Expertise and Experience to be considered to become a successful professional.
Now, if I will about the overall situation then DevOps will be the future but here to answer your question precisely the availability of DBA professional either Oracle and SQL is less than other two. Also, if you begin your career in DBA then, later on, you may move to Big Data, Business Intelligence as a career.
Whereas, you will find a good competition in Networking because a number of candidates are more.
Development has many branches and you need to decide which path you need to follow. As per current market trends as well as in future demand Java, Angular Js, Node Js, Python, Jquery and Apex would help you a lot in Cloud computing back-end programming and IoT.