Array
(
[1] => Array
(
[name] => Array
(
[0] => 贵州
[1] => 六盘水市
[2] => 钟山区
)
[num] => 1
)
[2] => Array
(
[name] => Array
(
[0] => 贵州
[1] => 贵阳市
[2] => 市辖区
)
[num] => 10
)
[3] => Array
(
[name] => Array
(
[0] => 贵州
[1] => 贵阳市
[2] => 花溪区
)
[num] => 1
)
)
想通过 数组里的 num 进行排序 ，升序和降序
