PHP插入是无法插入到mysql数据库中？

Question

我试图将输入文本字段的值插入到mysql数据库中，但无济于事！

我要做的是在product_name表格的product_name列中输入transactions值！

我不明白是什么阻止INSERT INTO执行！

有人可以看看这个，让我知道出了什么问题吗？

我甚至没有任何错误，所以我不知道出了什么问题！

<form action="order.php" method="post" name="shoppingcart">
    <?php 
    //We want to include the shopping cart in the email
    ob_start();
    ?>
    <table style="border-collapse:collapse;" width="100%" border="1">
      <tr>
        <th style="border-collapse:collapse;" scope="col">&nbsp;</th>
        <th scope="col">Item Name</th>
        <th scope="col">Unit Price</th>
        <th scope="col">Qty</th>
        <th scope="col">Cost</th>
      </tr>

        <?php 
        //Print all the items in the shopping cart
        // First we check to see if the form has been submitted 

   $totalAll = 0;
   $total = 0;
   $ship = $_POST['ship'];
    foreach ($_SESSION['SHOPPING_CART'] as $itemNumber => $item) {
if (isset($_POST['username'])){
    //Connect to the database through our include 
    include_once "config/connect.php";      

        // Add user info into the database table, claim your fields then values
        $sql = "INSERT INTO transactions (firstname, lastname, username, email, price, qty, product_name) 
        VALUES('$firstname','$lastname','$username','$email','$price','$qty','$product_name')" or die;
        $query = mysqli_query($db_conx, $sql);
        // Get the inserted ID here to use in the activation email
        $id = mysqli_insert_id($db_conx);
} 

    $totalAll = $totalAll + ($item['qty']*$item['price']);

    $total = $totalAll + $ship;
        ?>
        <tr id="item<?php echo $itemNumber; ?>">    
            <td><a href="order.php?remove=<?php echo $itemNumber; ?>">remove</a></td>
            <td><?php echo $item['name']; ?></td>
            <td>£<?php echo $item['price']; ?></td>
            <td><input name="items_qty[<?php echo $itemNumber; ?>]" type="text" id="item<?php echo $itemNumber; ?>_qty" value="<?php echo $item['qty']; ?>" size="2" maxlength="3" /></td>
            <td>£<?php echo $item['qty'] * $item['price']; ?></td> 
            <input name="price" type="hidden" id="" value="<?php echo $item['price']; ?>" size="2" maxlength="10" />
    <input name="qty" type="hidden" id="" value="<?php echo $item['qty']; ?>" size="2" maxlength="10" />
    <input name="product_name" type="txt" id="" value="<?php echo $item['name']; ?>" size="2" maxlength="10" />     
        </tr>
        <?php
        }
        ?>
    </table>
    </div>
            <?php $_SESSION['SHOPPING_CART_HTML'] = ob_get_flush(); ?>