如何将我添加的产品设为总价？

如何解决如何将我添加的产品设为总价？

如何使我添加的产品达到总价？

意思是我做了一些代码来降低某些产品的价格，但它不起作用？！

它只是在最后一个产品上打印我想要成为所有产品的总和

代码如下：

function.PHP

    function display_payers(){

    $total = 0;
    $category_query = query("SELECT * FROM payers WHERE payers_id  " . escape_string($id) . " ");
    confirm($category_query);
    
    while ($row = fetch_array($category_query)) {
 
        $sub             = $row['price'];
        $payers_id       = $row['payers_id'];
        $name            = $row['name'];
        $serial_number   = $row['serial_number'];
        $mobile_number   = $row['mobile_number'];
        $email           = $row['email'];
        $pass            = $row['pass'];
        $price           = $row['price'];
        
        $payer_photo = $row['payer_photo']; //**** */
        $user_show = $row['user_show']; //**** */
 
 
        $payer = <<<DELIMETER
        
        
        <tr>
        <td>{$payers_id}</td>
        <td>{$name}</td>
         <td>{$serial_number}</td>
         <td>{$mobile_number},<br>{$email},<br>{$pass}</td>
         <td>{$user_show}<br>
         <a>
             <img style="width: 80px; height="80px" src="../../resources/uploads/$payer_photo" alt="">
         </a>
     </td>
     <td>{$price}SR<br>
     </td>
         <td><a class="btn btn-default btn-number" href="index.PHP?edit_payer&id={$row['payers_id']}"><span class="glyphicon glyphicon-edit"></span></a></td>
 
         <td><a class="btn btn-default" href="index.PHP?delete_payers_id={$row['payers_id']}"><span class="glyphicon glyphicon-remove"></span></a></td>
    </tr>
DELIMETER;
 
        echo $payer;
    }
 
    $_SESSION['item_totals'] = $total += $sub;
}

解决方法

用它来添加小计

$_SESSION['item_totals'] += $sub;

减去

$_SESSION['item_totals'] -= $sub_value;