Abstract: Relational database management systems (RDBMSs) have traditionally been used to store and manage data from Internet, Intranet, or Desktop applications in order to serve multiusers systems. RDBMS has also been known to provide flexible services with a wide range of scalability. In traditional RDBMSs, role-based access control (RBAC) models have been implemented in commercial products like Oracle, MySQL, and PostgreSQL and many more with some variations from each other. Privacy is an important factor for data stores in addition to the security. The chapter discusses security of traditional database systems using an example of PostgreSQL database system. It explains RBAC and its variations with an example of PostgreSQL and describes the basic RBAC model in context of MongoDB. The chapter also explains the procedure to create user, roles, and functionalities provided in MongoDB for user authentication and access control. It explores possible modifications proposed for basic RBAC.