php - 在 php 中获取列的总和不起作用

Question

我试图获取 php 内列中的值的总和，但它根本不起作用，而在 MySQL 中测试时查询工作正常，这是代码(使用完整代码更新)

require('../_req/base.php');
$getCartQ = "select * from user_product inner join cart inner join products inner join users on user_product.User_ID = cart.User_ID and user_product.User_ID = users.User_ID group by cart.User_ID";
$getCartR = mysql_query($getCartQ);
?> <table align="center" width="1271" border="0" cellpadding="0" cellspacing="0">

 <?php
 while($cartRow = mysql_fetch_array($getCartR)){

     $sumQ = "select SUM(Total) as total from user_product where Status = 'active' and user_product.User_ID = '$cartRow[User_ID]'";
     $sumR = mysql_query($sumQ) or die(mysql_error());
     $sumRow = mysql_fetch_assoc($sumR);
     $cost = $sumRow['total'];
    ?>
    <tr>
    <td><?php echo $cartRow['Full_Name'] ?></td>
    <td><?php echo $cartRow['State']; ?></td>
    <td><?php echo $cost; ?></td>
    </tr>
    <?php 
 }
 ?>
 </table>
 <?php
mysql_close($connect);

当我尝试回显 $cost 时，我什么也没有得到，只是一个空格，该代码有什么问题？

Answer 1

 user_product.User_ID = '$getCartR[User_ID]'";

至

 user_product.User_ID = '{$getCartR['User_ID']}'";