title: Oracle: replace "rollup" in query with something else
body: <p>I need to rewrite a simple query without rollup function. Could you help me?</p>
  
  <p>This is an original query: </p>
  
  <pre><code>  SELECT e.department_id, 
           e.job_id, 
           SUM(e.salary)
      FROM EMPLOYEES e
  GROUP BY ROLLUP(e.department_id, e.job_id);
  </code></pre>
  
  <p>I guess it is possible to rewrite using UNION statement, yea?</p>