A very powerful feature of the Oracle database is Virtual Private Database (VPD). This feature is only available with the Enterprise edition. Virtual Private Database, also known as Row Level Security or Fine Grained Access Control, is a very popular choice of security when the standard object privileges and database roles are not sufficient. With VPD, you can specify which part (rows and/or columns) are accessible to the user. The policies that you specify can be as simple or complex as required.

VPD policies are defined against the database tables and are enforced whenever the table is accessed, regardless of the user interface that is being used. When the data is accessed through APEX or SQL*Plus, the same VPD policies are enforced and only the data is accessible, which is allowed by the policy.

When you define a VPD policy on a database table, a predicate is added whenever the table is accessed. With the VPD policy, you can define when the predicate is applied...