public function setOrderBy($order_by, $order = null)
    {
        $this->order_by = $order_by;

        $this->order = $order;

        return $this;
    }
public function setOrderBy($order_by, $order = null)
    {
        $this->order_by = $order_by;

        $this->order = $order;

        return $this;
    }
Set order by

@param string $order_by