title: COALESCE doesnt work with CodeIgniter
body: <p>I tried so many times but not any efficent.</p>
  <p><strong>My tried 3 queries:</strong></p>
  <pre><code> $query = $this-&gt;db-&gt;query(&quot;SELECT COALESCE(links.name, 'noname') as owner FROM links&quot;);
  
   $query = $this-&gt;db-&gt;query(&quot;SELECT COALESCE(links.name, users.username) as owner FROM links&quot;);
  
   $this-&gt;db-&gt;select(&quot;COALESCE(links.name, 'noname') as owner&quot;, false);
  </code></pre>
  <ol>
  <li>Users table joined</li>
  <li>Tried without join</li>
  <li>CodeIgniter version <code>2.1.4</code></li>
  <li>MySql version <code>5.5.24</code></li>
  </ol>
  <p>I just want show name which not <code>NULL</code>. If <code>links.name</code> is NULL, get <code>users.username</code></p>
  <p>But i couldnt figure out.</p>
  <h3>Result is always following</h3>
  <pre><code>  0 =&gt; 
      array (size=1)
        'owner' =&gt; string 'John Doe' (length=9)
    1 =&gt; 
      array (size=1)
        'owner' =&gt; string '' (length=0)
    2 =&gt; 
      array (size=1)
        'owner' =&gt; string '' (length=0)
  </code></pre>