Abstract: The present invention discloses a system, method, and device for unified access control on federated database. In one implementation, a federated system to provide a unified access control for the data stored in federated databases is disclosed. The federated system comprise at least one central access controller configured to receive at least a query plan generated; verify the query plan generated against at least a user rights pre-stored in at least one central authorization metadata table, a table and an associated column name from the query plan is verified; update, if the user rights pre-stored allow access to the query plan verified, the query plan generated; convert the query plan updated to at least a physical query for execution by at least one database; and execute the physical query to return at least a result for the federated query received.