Example 1: Granting and Revoking Roles

    SQL> -- Create three users and two roles. Oracle Rdb automatically
    SQL> -- generates users and roles if they are identified externally.
    SQL> CREATE USER ABLOWNEY IDENTIFIED EXTERNALLY;
    SQL> CREATE USER BGREMBO IDENTIFIED EXTERNALLY;
    SQL> CREATE USER LWARD IDENTIFIED EXTERNALLY;
    SQL> CREATE ROLE SALES_MANAGER IDENTIFIED EXTERNALLY;
    SQL> CREATE ROLE DIVISION_MANAGER IDENTIFIED EXTERNALLY;
    SQL> -- Grant the SALES_MANAGER role to users ABLOWNEY,
    SQL> -- BGREMBO, and to the DIVISION MANAGER ROLE.
    SQL> GRANT SALES_MANAGER TO ABLOWNEY, BGREMBO, DIVISION_MANAGER;
    SQL> -- Grant the DIVISION_MANAGER role to LWARD. LWARD now
    SQL> -- has both the SALES_MANAGER and DIVISION_MANAGER roles.
    SQL> GRANT DIVISION_MANAGER TO LWARD;
    SQL> -- Revoke the DIVISION_MANAGER role from LWARD. He has
    SQL> -- left the company.
    SQL> REVOKE DIVISION_MANAGER FROM LWARD;
    SQL> -- Grant the DIVISION_MANAGER role to BGREMBO.  She
    SQL> -- has been promoted to division manager.
    SQL> GRANT DIVISION_MANAGER TO BGREMBO;