递归获取所有子分类

    public function getSubs($categorys){
        foreach($categorys as $key=>$value){
            $children = Db::name('category')->where('parent_id',$value['id'])->select()->toArray();
            if(!empty($children)){
                $categorys[$key]['children'] = $this->getSubs($children);
            }
        }
        return $categorys;
    }
    public function gettree(){
        $parent_id = Request::param('parent_id',0);
        $categorys = Db::name('category')->where('parent_id',$parent_id)->select()->toArray();
        $categorys = $this->getSubs($categorys);
        dump($categorys);
    }

项目框架Think PHP

CREATE TABLE `tp_category`  (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `parent_id` int(11) UNSIGNED NOT NULL DEFAULT 0,
  `name` varchar(200) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = MyISAM AUTO_INCREMENT = 23 CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Dynamic;

INSERT INTO `tp_category` VALUES (1, 0, 'php');
INSERT INTO `tp_category` VALUES (2, 0, 'java');
INSERT INTO `tp_category` VALUES (3, 0, 'c/c++');
INSERT INTO `tp_category` VALUES (4, 1, 'php基础');
INSERT INTO `tp_category` VALUES (5, 1, 'php开源资料');
INSERT INTO `tp_category` VALUES (6, 1, 'php框架');
INSERT INTO `tp_category` VALUES (7, 2, 'java Se');
INSERT INTO `tp_category` VALUES (8, 2, 'java EE');
INSERT INTO `tp_category` VALUES (9, 2, 'java Me');
INSERT INTO `tp_category` VALUES (10, 3, 'c/c++基础编程');
INSERT INTO `tp_category` VALUES (11, 3, 'c/c++系统开发');
INSERT INTO `tp_category` VALUES (12, 3, 'c嵌入式编程');
INSERT INTO `tp_category` VALUES (13, 3, 'c++应用开发');
INSERT INTO `tp_category` VALUES (14, 13, 'c++桌面应用开发');
INSERT INTO `tp_category` VALUES (15, 13, 'c++游戏开发');
INSERT INTO `tp_category` VALUES (16, 6, 'ThinkPHP5.0');
INSERT INTO `tp_category` VALUES (17, 6, 'ThinkPHP5.1');
INSERT INTO `tp_category` VALUES (18, 6, 'ThinkPHP6.0');
INSERT INTO `tp_category` VALUES (19, 16, 'ThinkPHP5.0目录结构');
INSERT INTO `tp_category` VALUES (20, 16, 'ThinkPHP5.0路由');
INSERT INTO `tp_category` VALUES (21, 15, '游戏引擎开发');
INSERT INTO `tp_category` VALUES (22, 15, '游戏分类简介');

SET FOREIGN_KEY_CHECKS = 1;