public function addLeftJoin($table, $onPredicate, $tableAlias = '', $order = 20, $parameters = array())
    {
        if (!$tableAlias) {
            $tableAlias = $table;
        }
        $this->from[$tableAlias] = array(
            'type' => 'LEFT',
            'table' => $table,
            'filter' => array($onPredicate),
            'order' => $order,
            'parameters' => $parameters
        );
        return $this;
    }