public function bindValue($param, $value, $type=null)
    {
        $ok = false;
        try {
            $param = $this->_getBindVar($param);
            if (PDO::PARAM_LOB == $type) {
                $lob = \oci_new_descriptor($this->_con, \OCI_D_LOB);
                $ok  = \oci_bind_by_name($this->_stmt, $param, $lob, -1, \OCI_B_BLOB);
                $this->_bindsLob[$param] = array(
                    'lob'   => $lob,
                    'value' => $value,
                );
            } else {
                $ok = \oci_bind_by_name($this->_stmt, $param, $value);
                $this->_binds[$param] = $value;
            }
        } catch (\Exception $e) {
            throw new \PDOException($e->getMessage());
        }
        return $ok;
    }