问使用SQL在PHP和HTML中运行总计

EN

<?php 
  session_start();
  $pageName="Order";
  require_once("header.php");
  require_once("serverCode/checklogin.php");
  require_once("serverCode/connect.php"); 
?>

<h2>Order Quantity</h2>
<!--Contact information-->
<form method='post'>
  <h3>Contact Information:</h3>   
    <div id="errorMessage" class='errorMessage' style="color:white;"></div>
<div>    
  <div class='formInput percent50'>First name:<br>
  <?php echo "<input type='text' name='txtFirstName' id='txtFirstName' value='" . $_SESSION['userFirstName'] ."'>"; ?></div>

  <div class='formInput percent50'>Last name:<br>
  <?php echo "<input type='text' name='txtLastName' id='txtLastName' value='" . $_SESSION['userLastName'] ."'>"; ?></div>

  <div class='formInput percent100'>Address:<br>
  <?php echo "<input type='text' name='txtAddress' id='txtAddress' value='" . $_SESSION['userAddress'] ."'>"; ?></div>

  <div class='formInput percent50'>City:<br>
  <?php echo "<input type='text' name='txtCity' id='txtCity' value='" . $_SESSION['userCity'] ."'>"; ?></div>

  <div class='formInput percent50'>Postal Code:<br>
  <?php echo "<input type='text' name='txtPostalCode' id='txtPostalCode' value='" . $_SESSION['userPostalCode'] ."'>"; ?></div>

  <div class='formInput percent100'>Email:<br>
  <?php echo "<input type='text' name='txtEmail' id='txtEmail' value='" . $_SESSION['userEmail'] ."'>"; ?></div>
</div>

  <div class='formInput percent100'>Notes:<br>
  <?php echo "<input type='text' name='txtNotes' id='txtNotes' value='" . 'notes' ."'>"; ?></div>
</div>

<?php
//Create a table to fill in
  echo("<table border=1>");
  echo("<tr><th>Image</th><th>Name</th><th>Product Description</th>    <th>Cost</th>    <th>Order</th><th>Total</th></tr>");
  require_once("serverCode/connect.php");
  $sql = "Select * FROM products;";

  $result = $mysqli->query($sql);
  while($row = $result->fetch_assoc()) {
    // jQuery associate number with the textbox for each product
    //dynamic on the fly (after is simpler )
    $id = $row['productsID'];
    $productsName = $row['productsName'];
    $productsDesc = $row['productsDesc'];
    $productsCost = $row['productsCost'];
    $productQty = $productQty;
    echo("<tr>");
    echo("<td>" . "<img src='images/" . $id . ".jpg'"    . "</td>");
    echo("<td>" . $productsName . "</td>");
    echo("<td>" . $productsDesc . "</td>");
    echo("<td>" . $productsCost . "</td>");
    echo("<td><input type=number>" . $productQty.  "</td>");
    echo("<td>" . $productsCost * $productQty . "</td>");
    //display a running total
    echo("</tr>");
    }
  echo("</table>")      
?>
  <script src="clientCode\validate.js"></script>
  </form>

<div>
  <input type="submit" value="Submit Order">
    </div>
<?php require_once("footer.php"); ?>