对二维数组中的某个键进行排序, 通过  PHP自带的函数 array_multisort 来实现

$arr = array(
       ["id"=>1,"score"=>32],
       ["id"=>2,"score"=>56],
       ["id"=>3,"score"=>38],
       ["id"=>4,"score"=>27],
       ["id"=>5,"score"=>45],
       ["id"=>6,"score"=>20],
       ["id"=>7,"score"=>35],
  	);
foreach ($arr as $key => $value) {
	$name[$key] = $value['score'];
}
array_multisort($name, $arr);

$i = 0;
foreach($arr as $row){
	$i++;
	$row["sort"] = $i;  //增加个排序后的名次
	$temp[] = $row;
}
print_r($temp); //$temp 就是最后排好的顺序