php pdo 链接数据库

/链接数据库        $servername = "localhost";        $username = "root";        $password = "111111";        try {            $conn = new PDO("mysql:host=$servername;dbname=kuaijiezhou", $username, $password);            $conn->exec("SET NAMES 'utf8';");                //echo "Connected successfully";         }        catch(PDOException $e)        {            echo $e->getMessage();        }$orderid = $_GET['orderid']  ? intval($_GET['orderid']) : ''; //用户id        //查询订单        $url1 = "SELECT * FROM my_order where id = $orderid";        $res_order = $conn->query($url1)->fetch(PDO::FETCH_ASSOC);        //订单配送时间        $url2 = "SELECT * FROM my_ordersendtime where orderid = $orderid";        $res_order_sendtime = $conn->query($url2)->fetch(PDO::FETCH_ASSOC);        //订单详情        $url3 = "SELECT * FROM my_orderdetail where orderid = "."'".$res_order['orderid']."'";        $res_order_detail = $conn->query($url3)->fetchAll(PDO::FETCH_ASSOC);