array_multisort 排序

$bonusdata = $bonusDb->gets($where)->items;
foreach ($bonusdata as $key => $val) {
   $tmpArr[$key] = $val['bonus'];
}
array_multisort($tmpArr, SORT_DESC, $bonusdata);
foreach ($bonusdata as $key => $val) {
   $bonusDb->setPkid($val['id']);
   $bonusDb->set('ranking', $key + 1);
   if ($bonusDb->save() === false) {
      return false;
   }
}