主要应用领域：无限极分类的菜单栏、对评论进行无限次追评 ...
1、数据库设计要求：每一条记录都需要存在id（主键）和pid（父用户id）字段。
2、查询数据库获取所有的记录组成的数组。
3、递归组合成新的数组
//封装成类里面的方法//$data表示所有的记录组成的数组。&寻址增加查询效率。public function getTree(&$data, $parentId = 0){$tree = [];foreach($data as $k => $v){if($v[‘pid‘] == $parentId){ //父亲找到儿子$v[‘child‘] = self::getTree($data, $v[‘id‘]); //封装成函数的时候，需要去掉self::这个标识。 ?$tree[] = $v;unset($data[$k]); // 释放原始数据变量}}return $tree;}4、显示结果举例
排序前：
array(8) {[0] => array(6) {["id"] => int(1)["memb_id"] => int(4)["content"] => string(13) "回复内容1"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)}[1] => array(6) {["id"] => int(2)["memb_id"] => int(4)["content"] => string(13) "回复内容2"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)}[2] => array(6) {["id"] => int(3)["memb_id"] => int(4)["content"] => string(13) "回复内容3"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)}[3] => array(6) {["id"] => int(4)["memb_id"] => int(4)["content"] => string(13) "回复内容4"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(1)}[4] => array(6) {["id"] => int(5)["memb_id"] => int(4)["content"] => string(13) "回复内容5"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(4)}[5] => array(6) {["id"] => int(6)["memb_id"] => int(4)["content"] => string(13) "回复内容6"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(4)}[6] => array(6) {["id"] => int(7)["memb_id"] => int(4)["content"] => string(13) "回复内容7"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(5)}[7] => array(6) {["id"] => int(8)["memb_id"] => int(4)["content"] => string(13) "回复内容8"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(6)}}排序后：
array(3) {[0] => array(7) {["id"] => int(1)["memb_id"] => int(4)["content"] => string(13) "回复内容1"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)["child"] => array(1) {[0] => array(7) {["id"] => int(4)["memb_id"] => int(4)["content"] => string(13) "回复内容4"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(1)["child"] => array(2) {[0] => array(7) {["id"] => int(5)["memb_id"] => int(4)["content"] => string(13) "回复内容5"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(4)["child"] => array(1) {[0] => array(7) {["id"] => int(7)["memb_id"] => int(4)["content"] => string(13) "回复内容7"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(5)["child"] => array(0) {}}}}[1] => array(7) {["id"] => int(6)["memb_id"] => int(4)["content"] => string(13) "回复内容6"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(4)["child"] => array(1) {[0] => array(7) {["id"] => int(8)["memb_id"] => int(4)["content"] => string(13) "回复内容8"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(6)["child"] => array(0) {}}}}}}}}[1] => array(7) {["id"] => int(2)["memb_id"] => int(4)["content"] => string(13) "回复内容2"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)["child"] => array(0) {}}[2] => array(7) {["id"] => int(3)["memb_id"] => int(4)["content"] => string(13) "回复内容3"["add_time"] => int(1500622839)["ask_id"] => int(1)["pid"] => int(0)["child"] => array(0) {}}}【PHP原生】递归实现无限级分类树状展示数据
原文地址：https://www.cnblogs.com/php99/p/9796969.html