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);