PHP二位数组/多维数组 根据某个键值排序

$arr[$i]['FirstName'] = $d_first_name;
$arr[$i]['MiddleName'] = $d_middle_name;
$arr[$i]['LastName'] = $d_last_name;
$arr[$i]['Company'] = $d_company;
$arr[$i]['ProcessDate'] = $auth_table->getUpdatedAt();

foreach ($arr as $key => $val) {  //get ProcessDate from array
$tmp[$key] = $val['ProcessDate'];
}
array_multisort($tmp, SORT_DESC, $arr);  //sort desc

然后数组按照ProcessDate倒序排列