title: How to group by DESC order
body: <p>I have the following table called questions:</p>
  <pre><code>ID | asker 
  1  | Bob
  2  | Bob
  3  | Marley
  </code></pre>
  <p>I want to select each asker only once and if there are multiple askers with the same name, select the one of the highest id. So, the expected results:</p>
  <pre><code>ID | asker 
  3  | Marley
  2  | Bob
  </code></pre>
  <p>I use the following query:</p>
  <pre><code>SELECT * FROM questions GROUP by questions.asker ORDER by questions.id DESC
  </code></pre>
  <p>I get the following result:</p>
  <pre><code>ID | asker 
  3  | Marley
  1  | Bob
  </code></pre>
  <p>It selects the first 'Bob' it encounters instead of the last one.</p>