title: Zend framework Undefined class constant '' in Zend/Db/Select.php
body: <p>There is a srange error in my Apache Log : </p>
  
  <p>PHP Fatal error: Undefined class constant ''</p>
  
  <p>This is on line 814 of de library (Zend framework 1.11) library/Zend/Db/Select.php</p>
  
  <p>A look of the code : </p>
  
  <blockquote>
    <p><code>if ($type == self::FROM) {<br>
          // append this from after the last from joinType<br>
         $tmpFromParts = $this-&gt;_parts[self::FROM];<br>
         $this-&gt;_parts[self::FROM] = array();<br>
         // move all the froms onto the stack<br>
         while ($tmpFromParts) {<br>
             $currentCorrelationName = key($tmpFromParts);<br>
             if ($tmpFromParts[$currentCorrelationName]['joinType'] != self::FROM) {<br>
                            break;<br>
             }<br>
             $lastFromCorrelationName = $currentCorrelationName;<br>
             $this-&gt;_parts[self::FROM][$currentCorrelationName] = array_shift($tmpFromParts);<br>
        }     } 
    </code></p>
  </blockquote>
  
  <p>That's strange because the undefined constant is empty.
  THis fatal error appears some times but not at every load of pages.
  Is it a release BUG of the zend framework?</p>