php处理三级分类数据

<?php
//瞎写的
// 链接数据库
$link = mysqli_connect('localhost','root','root');
if($link == null){
　　exit;
}
mysqli_select_db($link,'test');
$link->query("SET NAMES utf8");
$sql = "select * from tp_goods_categorys";
$res = mysqli_query($link,$sql);

while($res && $row = mysqli_fetch_assoc($res)) {
  $list[] = $row;
}
echo '<pre>';
print_r(res($list));
function res($items){
    $tree = array();
    foreach($items as $key =>$val){
            $list = explode(',',$val['categorys_path']);
            switch(count($list)){
                case 1:
                    $tree[$val['id']] = $val;
                    break;
                case 2:
                    $tree[$val['categorys_pid']]['son'][$val['id']] = $val;
                    break;
                case 3:
                    $tree[$list[1]]['son'][$list[2]]['son'] = $val;
                    break;
            }
    }
    return $tree;
}

<?php
//递归
$array = array(
array('id' => 1, 'pid' => 0, 'name' => '湖北省'),
array('id' => 2, 'pid' => 0, 'name' => '北京市'),
array('id' => 3, 'pid' => 1, 'name' => '武汉市'),
array('id' => 4, 'pid' => 2, 'name' => '朝阳区'),
array('id' => 5, 'pid' => 2, 'name' => '通州区'),
array('id' => 6, 'pid' => 4, 'name' => '望京'),
array('id' => 7, 'pid' => 4, 'name' => '酒仙桥'),
array('id' => 8, 'pid' => 3, 'name' => '武昌区'),
array('id' => 9, 'pid' => 1, 'name' => '武安市'),
);

function cation($arr,$num=0,$m=1)
{
    $list = [];
    foreach($arr as $k=>$v){
        if($v['pid'] === $num){
            $v['level'] = $m;
            $v['son'] = cation($arr,$v['id'],$m+1);
            $list[] = $v;

        }
    }
    return $list;
}

$list = cation($array);
echo '<pre>';
print_r($list);
echo '</pre>';