PHP:Form在用户登录后停止传递数据

我想对页面上的项目进行排序，为此我使用以下表格：

<form method="get" action="">
            <label for="sort">Sort items by</label>
            <select id="sort" name="sort">
                <option value="">-</option>
                <option value="plth">Price (Low to high)</option>
                <option value="phtl">Price (High to low)</option>
                <option value="naz">Name (A-Z)</option>
                <option value="nza">Name (Z-A)</option>
            </select>
            <input type="submit" name="sortSubmit" value="GO >">
        </form> 

按项目排序
-
价格（从低到高）
价格（从高到低）
名称（A-Z）
名称（Z-A）

处理表单后，我将使用一些sql语句从数据库中按所需顺序检索项目：

if(isset($_GET["sortSubmit"]) && $_GET["sort"] == "plth") {
                    $retrieve = "SELECT * FROM products WHERE ID <= '9' ORDER BY PRICE ASC";
                }
                elseif (isset($_GET["sortSubmit"]) && $_GET["sort"] == "phtl") {
                    $retrieve = "SELECT * FROM products WHERE ID <= '9' ORDER BY PRICE DESC";
                }
                elseif (isset($_GET["sortSubmit"]) && $_GET["sort"] == "naz") {
                    $retrieve = "SELECT * FROM products WHERE ID <= '9' ORDER BY NAME ASC";
                }
                elseif (isset($_GET["sortSubmit"]) && $_GET["sort"] == "nza") {
                    $retrieve = "SELECT * FROM products WHERE ID <= '9' ORDER BY NAME DESC";
                }

if（isset（$\u GET[“sortSubmit”]）&&&$\u GET[“sort”]=“plth”）{
$retrieve="从ID所在的产品中选择*如果此代码起作用，问题是其他HTML，这些SQL查询与登录的用户无关。显示您如何登录用户。什么是“停止工作”？任何错误？空白页？…？我的意思是项目的排序停止工作，因为用户登录后表单不再传递任何数据。显示告诉我们您如何让用户登录到您的应用程序的代码。只需编辑以下问题：）您是否可以发布更多包含处理部分的页面（从包含
if（isset（$\u GET[“sortSubmit”]）&&$\u GET[“sort”]=“plth”）等的页面顶部）？
<?php
session_start();
ob_start();
include("includes/constants.php");
include("includes/config.php");
if(isset($_POST['accountLogin'])) {
    $query_login = "SELECT * FROM users WHERE password = ' ".$_POST['accountPass']." ' and email = ' ".$_POST['accountEmail']." ' ";
    $sql_login = mysqli_query($connection, $query_login);
    if(mysqli_num_rows($sql_login) > 0) {
        $login_data = mysqli_fetch_array($sql_login);
        //echo $login_data['firstName'] . $login_data['lastName'];
        //echo $login_data['email'];
        $_SESSION['userID'] = $login_data['ID'];
        $_SESSION['userEMAIL'] = $login_data['email'];
        $_SESSION['userNAME'] = $login_data['firstName'].$login_data['lastName'];
        setcookie('userID', $login_data['ID'], time() + (60 * 60 * 60 * 3));
        setcookie('userEMAIL', $login_data['email'], time() + (60 * 60 * 60 * 3));
    }
    else {
        echo '<div id="wrongHidden" style="text-align:center;width:200px;height:300px;position:fixed;top:53px;right:4.4%;background:#dedede;color:red;border:1px solid black;z-index:55;    border-radius:5px;padding:15px 10px 15px 10px;font-size:20px;">Incorrect password or email!<br><br><button type="button" class="btn" style="border:1px solid black;position:absolute;bottom:5px;left:15px;width:190px;" onclick="hideBtn()">OK</button></div>';
    }
}

<?php 
ob_start();
include("header.php");
include("includes/config.php"); 
//ADDING THE PRODUCTS TO THE CART:
if(isset($_GET['action']) && $_GET['action'] == "add") {
    if(isset($_GET['pid'])) {
        $pid = intval($_GET['pid']); 
        if(isset($_SESSION['cart'][$pid])) {
            $_SESSION['cart'][$pid]['quantity']++;
        }
        else {
            $sql = "SELECT * FROM products WHERE ID = ($pid)";
            $do_query = mysqli_query($connection, $sql);
            if(mysqli_num_rows($do_query) > 0) {
                $product_row = mysqli_fetch_array($do_query);
                $_SESSION['cart'][$product_row['ID']] = array("quantity" => 1, "price" => $product_row['PRICE']);
            }
            else {
                echo 'Invalid product!';
            }
        }
    }   
}
// END OF ADDING THE PRODUCTS TO THE CART
?>