title: Failed to Select data with query builder
body: <p>I Want to select data from 2 tables with query builder yii framework. SO my script is below</p>
  
  <pre><code>$result = $command-&gt;select( array('a.parameter_name', 'a.unit', 'b.result', 'b.normal_value'))
                  -&gt;from('parameter a')
                  -&gt;join('test b', 'a.parameter_id = b.parameter_id')
                  -&gt;where('b.noRM='.$_POST['no_rm'])
                  -&gt;queryAll();
  </code></pre>
  
  <p>When I <code>echo</code> the result, I only get <code>parameter_id</code>. </p>
  
  <pre><code>foreach($result as $row){
     $name = $row['parameter_name'];
     $unit = $row['unit'];
     $normal_value = $row['normal_value'];
  }
  </code></pre>
  
  <p>I get this error. </p>
  
  <blockquote>
    <p>Error 500</p>
    
    <p>Undefined index: parameter_name.</p>
  </blockquote>
  
  <p>How can I fix it?</p>