$this->sql_select     = 'part1, part2, description';
$this->sql_orderby    = 'part1, part2';
$this->sql_ordery_seq = 'asc';
$data = $this->getData(null);

// convert each row into 'id=desc' in the output array
foreach ($data as $row => $rowdata) {
    $key = $rowdata['part1].'/'.$rowdata['part2'];
    $array[$key] = $rowdata['description'];
} // foreach

return $array;