title: Get the greatest element for each group of result
body: <p>I have the following fields: <code>user_id, app_mod, profile, update_date</code>.
  The first three fields can be duplicated (i.e. two rows could have <code>user_id, app_mod and profile</code> equals, but different <code>update_date</code>):</p>
  
  <pre><code>user_id   app_mod  profile update_date
  560047    RI03290   22809   14-GEN-10  
  560047    RI03290   22809   18-GEN-10
  </code></pre>
  
  <p>How can I get the one row with higher <code>update_date</code> in an Oracle environment?</p>
  
  <pre><code>560047    RI03290     22809   18-GEN-10
  </code></pre>