/**
  * Set the ORDER BY clause of this query
  *
  * @see SQLSelect::orderby()
  *
  * @param String $sort Column to sort on (escaped SQL statement)
  * @param String $direction Direction ("ASC" or "DESC", escaped SQL statement)
  * @param Boolean $clear Clear existing values
  * @return DataQuery
  */
 public function sort($sort = null, $direction = null, $clear = true)
 {
     if ($clear) {
         $this->query->setOrderBy($sort, $direction);
     } else {
         $this->query->addOrderBy($sort, $direction);
     }
     return $this;
 }