Database Security is very important part in every domain whether it is industrial, civilian or it is government domain. As number of records or data is increasing it is very difficult to manage manually so database security is very crucial. Therefore, it is very important for every organization that how they deal with their data and how they secure their data from malicious users. Database uses schemas and security domains to control the access to the data and to restrict the use of various database resources. The database systems provide the privileges mechanism through which roles can be managed. The Roles are the named group of privileges that the authors grant to the users or some other roles of the system. In this paper the authors present the mechanism to improve database security and discuss the database users, schemas, privileges, roles, authentication and authorization.