title: Add results from several COUNT queries
body: <p>I am trying to fetch the sum of several counts in one query:</p>
  
  <pre><code>SELECT(
      SELECT COUNT( * )
      FROM comments +
      SELECT COUNT( * )
      FROM tags +
      SELECT COUNT( * )
      FROM search
  )
  </code></pre>
  
  <p>I am missing something here. I get syntax error.</p>