SELECT last_name, salary + NVL(commission_pct, 0), 
   job_id, e.department_id
/* Select all employees whose compensation is
greater than that of Pataballa.*/
  FROM employees e, departments d
       /*The DEPARTMENTS table is used to get the department name.*/
  WHERE e.department_id = d.department_id
    AND salary + NVL(commission_pct,0) >   /* Subquery:       */
   (SELECT salary + NVL(commission_pct,0)
                 /* total compensation is salar + commission_pct */
      FROM employees 
      WHERE last_name = 'Pataballa');

SELECT last_name,                    -- select the name
    salary + NVL(commission_pct, 0),-- total compensation
    job_id,                         -- job
    e.department_id                 -- and department
  FROM employees e,                 -- of all employees
       departments d
  WHERE e.department_id = d.department_id
    AND salary + NVL(commission_pct, 0) >  -- whose compensation 
                                           -- is greater than
      (SELECT salary + NVL(commission_pct,0)  -- the compensation
    FROM employees 
    WHERE last_name = 'Pataballa')        -- of Pataballa.
;
