title: SQL: how to use UNION and order by a specific select?
body: <p>I have two selects:</p>
  
  <pre><code>SELECT id FROM a -- returns 1,4,2,3
  UNION
  SELECT id FROM b -- returns 2,1
  </code></pre>
  
  <p>I'm receiving correct num of rows, like: <code>1,4,2,3</code>.</p>
  
  <p>But I want <code>b</code> table results first: <code>2,1,4,3</code> or <code>2,1,3,4</code></p>
  
  <p>How can I do this?</p>
  
  <p>(I'm using Oracle)</p>