//对数组$hotcat按照count键值大小降序进行排序；
$hotcat =array(
 array('1501'=>array('catid'=>'1546','catname'=>'数组排序 一级','count'=>'588')),
 array('1501'=>array('catid'=>'1546','catname'=>'数组排序二级','count'=>'588')),
 array('1501'=>array('catid'=>'1546','catname'=>'数组排序 三级','count'=>'588'))
);
//提取列数组；
foreach ($hotcat as $key => $val) {
 $tmp[$key] = $row['username'];
}
array_multisort($tmp,SORT_DESC,$hotcat);此处对数组进行降序排列；SORT_DESC按降序排列

//指定数组以$keys键值排序
function array_sort($array,$keys,$type='asc'){
//$array为要排序的数组,$keys为要用来排序的键名,$type默认为升序排序
$keysvalue = $new_array = array();
foreach ($array as $k=>$v){
$keysvalue[$k] = $v[$keys];
}
if($type == 'asc'){
asort($keysvalue);
}else{
arsort($keysvalue);
}
reset($keysvalue);
foreach ($keysvalue as $k=>$v){
$new_array[$k] = $array[$k];
}
return $new_array;
}
$hot_cat = array_sort($hot_cat,'count','desc'); //此处对数组进行降序排列