There are four levels of authentication that can restrict access to the different tables and databases: 1.Operating level authentication: This is the overall higher level access restriction to the application. Without this one cannot get access to the application. 2.Table authentication: The table level authentication is the access permissions set for each physical table. 3.Database authentication: The Database user and password, corresponding previleges can let someone to access specific db or can just give him only partial access. This authentication is the main thing for the application that coordinates different databases. 4.LDAP authentication.