原生类实现二级导航

<?php

    class mypdo{

        public $link;

        public $host;

        public $dbname;

        public $user;

        public $pwd;

        public $char;

        public function __construct($host,$dbname,$user,$pwd){

            $this->host=$host;

            $this->dbname=$dbname;

            $this->user=$user;

            $this->pwd=$pwd;

            $this->char='set names utf8';

            $this->link=new pdo("mysql:host={$this->host};dbname={$this->dbname}",$this->user,$this->pwd);

            $this->link->query($this->char);

        }

        public function query($sql){

            return $this->link->query($sql);

        }

        public function getAll($sql){

            return $this->query($sql)->fetchAll(PDO::FETCH_ASSOC);

        }

        public function getnum($sql){

            return $this->query($sql)->rowCount();

        }

    }

---

    $pdo=new mypdo("localhost","news","root","");

    $sql='select * from newstype';

    $rs=$pdo->getAll($sql);

    $data=[];

    foreach($rs as $v){

        $sql='select * from news where typeid='.$v['typeid'];

        $rk=$pdo->getAll($sql);

        $data[]= [

            'info'=>$v,

            'con' =>$rk

        ];

    }

    foreach($data as $v){

        echo $v['info']['typename'].'<br>';

        foreach($v['con'] as $s){

            echo $s['title'].'<br>';

        }

        echo "<hr>";

    }    

?>