Example 2-30 Using the Function NVL

DECLARE
   the_manager employees.manager_id%TYPE;
   name employees.last_name%TYPE;
BEGIN
-- NULL is a valid argument to NVL. In this case, manager_id is null
-- and the NVL function returns -1.
   SELECT NVL(manager_id, -1), last_name
      INTO the_manager, name FROM employees WHERE employee_id = 100;
   DBMS_OUTPUT.PUT_LINE(name || ' is managed by employee Id: ' || the_manager);
END;
/