The cloud data base service is a boon to the global technology which support various internet based application. But the serious issue behind this approach is the data confidentiality which threats the user’s dealing with the sensitive data’s. In order to overcome this problem, the authors propose a novel approach of adaptive encryption of cloud databases. That ensures the data security along with cloud database structure flexibility at design time. They have taken DataBase-as-a-Service (DBaaS) and compute their proposed cost estimation model to overcome the several security challenges according to the real-time scenario.