PHP 使用主键和辅助键对多维数组进行排序[重复]

如何按主键和辅助键对多维数组进行排序？ 例如，假设有以下数组：

$result = array();

$result[0]["prio"] = 1;
$result[0]["date"] = '2010-02-28';
$result[0]["post"] = "February's thoughts";

$result[1]["prio"] = 0;
$result[1]["date"] = '2010-04-20';
$result[1]["post"] = "April's thoughts";

$result[2]["prio"] = 0;
$result[2]["date"] = '2010-05-30';
$result[2]["post"] = "May's thoughts";

我希望将“prio”列排序为主键（升序）和“日期”作为辅助键（降序），得到：

$result[0]["prio"] = 0;
$result[0]["date"] = '2010-05-30';
$result[0]["post"] = "May's thoughts";
$result[1]["prio"] = 0;
$result[1]["date"] = '2010-04-20';
$result[1]["post"] = "April's thoughts";
$result[2]["prio"] = 1;
$result[2]["date"] = '2010-02-28';
$result[2]["post"] = "February's thoughts";

如何实现这一目标？

像这样使用 usort：

$result = array();

$result[0]["prio"] = 1;
$result[0]["date"] = '2010-02-28';
$result[0]["post"] = "February's thoughts";

$result[1]["prio"] = 0;
$result[1]["date"] = '2010-04-20';
$result[1]["post"] = "April's thoughts";

$result[2]["prio"] = 0;
$result[2]["date"] = '2010-05-30';
$result[2]["post"] = "May's thoughts";

function fct($a ,$b) {

  if ($a['prio'] < $b['prio']) {
    return -1;
  } elseif  ($a['prio'] > $b['prio']) {
    return 1;
  } else {
    return strcmp($b['date'], $a['date']);
  }

}

usort($result, "fct");
print_r($result);

Output:

Array
(
    [0] => Array
        (
            [prio] => 0
            [date] => 2010-05-30
            [post] => May's thoughts
        )

    [1] => Array
        (
            [prio] => 0
            [date] => 2010-04-20
            [post] => April's thoughts
        )

    [2] => Array
        (
            [prio] => 1
            [date] => 2010-02-28
            [post] => February's thoughts
        )

)