如何獲得購物車中相同用戶ID的兩個值的總和

Question

我一直在製作一個小型購物車。我試圖顯示購物車 價值，並有總計。我已成功顯示購物車產品，但我無法顯示總計。它一直在顯示錯誤'資源ID＃5'。請在下面查看我的代碼。

viewcart.php

<?php 

include('config.php'); 

session_start(); 

echo $session=$_SESSION['user_email']; 

echo $query=mysql_query("SELECT product_price, SUM(product_price) FROM cart where user_email='$session' GROUP BY user_email"); 


$total = mysql_fetch_array($query); 



$query1=mysql_query("select * from cart where user_email='$session'"); 
    $num_rows = mysql_num_rows($query1); 


    if($num_rows>0){ 

    echo "<center>"; 

    echo "<table style='width:80%' border=5px><tr><th>Product Name</th> 
<th>Product Details</th><th>Product Price</th></tr>"; 


    while($query2=mysql_fetch_array($query1)) 
    //if($query2>0){ 
    { 


    echo "<tr><td>".$query2['product_name']."</td>"; 

    echo "<td>".$query2['product_details']."</td>"; 

    echo "<td>".$query2['product_price']."</td>"; 

    echo "<td><a href='remove.php?id=".$query2['id']."'>Remove Product</a></td>"; 

    echo "</tr>"; 

    } 

    echo "<tr><td>Total:</td><td>".$total['product_price']."</td></tr>"; 


     ?> 

     </table> 


    </center><br/><br/><?php } else { echo "<center>No product available for display!!</center>"; }?> 

Answer 1

$query = mysql_query("SELECT SUM(product_price) as sum FROM cart where user_email='".mysql_real_escape_string($session)."'"); 

$total = 0; 
if ($result=mysql_fetch_assoc($query)) { 
    $total = $result['sum']; 
}