PHP提交页面完全空白

我通过表单提交购买（我称之为订单）。我完全相信这部分工作正常，但是需要将购买插入数据库的页面是错误的。然而，我真的不知道哪里出了问题，为什么它只给我一个空白页面（addorder.php，处理页面），而它应该在上一页给我一条错误消息。以下是addorder.php的代码：

<?php

class PurchaseOrder
{
    private $db_connection = null;

    public $errors = array();

    public $messages = array();

    public function __construct()
    {
        if (isset($_POST["purchase"])) {
            $this->addOrder();
        }
    }

    private function addOrder()
    {
        if (empty($_POST['order_firstname'])) {
            $this->errors[] = "Please fill in your first name.";
        } elseif (empty($_POST['order_lastname'])) {
            $this->errors[] = "Please fill in your last name."; 
        } elseif (empty($_POST['order_phone'])) {
            $this->errors[] = "Please fill in your phone number.";  
        } elseif (empty($_POST['order_address'])) {
            $this->errors[] = "Please fill in your address.";
        } elseif (empty($_POST['order_city'])) {
            $this->errors[] = "Please fill in your city.";  
        } elseif (empty($_POST['order_postalcode'])) {
            $this->errors[] = "Please fill in your postal code.";
        } elseif (empty($_POST['order_deliverydate'])) {
            $this->errors[] = "Please fill in a delivery date you like.";               
        } elseif (empty($_POST['order_country'])) {
            $this->errors[] = "Please choose your country.";

            $this->db_connection = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);

            if (!$this->db_connection->set_charset("utf8")) {
                $this->errors[] = $this->db_connection->error;
            }

            if (!$this->db_connection->connect_errno) {

                $lastorder= "SELECT orderNumber FROM orders ORDER BY orderNumber DESC LIMIT 1";
                $lastordernumber=mysql_query($lastorder);

                while ($row=mysql_fetch_array($lastordernumber)) {
                    $lastnumber = $row['orderNumber'];
                }

                $order_firstname = $_POST['order_firstname'];
                $order_lastname = $_POST['order_lastname'];
                $order_phone = $_POST['order_phone'];
                $order_address = $_POST['order_address'];
                $order_city = $_POST['order_city'];
                $order_postalcode = $_POST['order_postalcode'];
                $order_deliverydate = $_POST['order_deliverydate'];
                $order_country = $_POST['order_country'];
                $order_date = date("Y-m-d");

                $customernumber = $_SESSION['CustomerNumber'];

                    $sql = "INSERT INTO orders (orderNumber, orderDate, requiredDate, shippedDate, status, comments, customerNumber) VALUES('" . $lastnumber . "', '" . $order_date . "', null, null, null, null, '" . $customernumber . "');";

                    $query_new_order = $this->db_connection->query($sql);

                    if ($query_new_order) {
                        $this->messages[] = "Your profile has been updated succesfully!";
                    } else {
                        $this->errors[] = "Sorry, your registration failed. Please go back and try again.";
                    }
            } else {
                $this->errors[] = "Sorry, no database connection.";
            }
        } else {
            $this->errors[] = "An unknown error occurred.";
        }
    }
}

---

空白页最常见的原因是缺少行终止符
。。。或者对你来说，可能太多了

$sql=“插入订单（订单号、订单日期、需求日期、发货日期、状态、注释、客户编号）值（“$lastnumber.”、“$order_date.”、null、null、null、“$customerNumber.”）

在SQL语句的末尾，您有一个不必要的
这可能就是你的代码被弄乱的原因

它应该是
$customernumber。"')";
打开文件后立即将错误报告添加到文件顶部
^yep，空白页检查器^authorized userecho？！回声？-我没有听到回声。你喜欢山姆吗@Jayblanchard为什么要使用
while
循环来读取限制为1的查询的结果？^被这么多Ralph错过了！我应该更仔细地看一下@Fred ii，SQL查询允许以
结尾即使这是问题所在，为什么会导致空白页？SQL语法错误不会导致PHP脚本失败
query（）
发生这种情况时只返回
false
。它仍然不起作用，但我编辑了我的帖子。你能告诉我怎么了吗？