protected function executeQuery($query)
        {
            $res = @odbc_exec($this->_lnk, $query);
            if(!$res) {
                $error = odbc_errormsg($this->_lnk);
                $this->log('Query failed: '.$error);
                throw new Exception('Executing query failed ' . $error, self::QUERY_FAILED);
            }
            return $res;
        }