Hello I am new to php and I have a problem, I have a code below that shows the fields in my order_details table in my database, the problem is in the

                                         <tr>

                                            <td><?php echo $product_row['name']; ?></td>
                                            <td><?php echo $member_row['Firstname']." ".$member_row['Lastname']; ?></td>
                                            <td><?php echo $cart_row['price']; ?></td>
                                            <td><?php echo $cart_row['qty']; ?></td>
                                            <td><?php echo $cart_row['total']; ?></td>
                                            <td><?php echo $cart_row['status']; ?></td>
                                            <td><?php echo $cart_row['modeofpayment']; ?></td>

                                            <form action="update_sir.php" method="get">
                                            <td ><input type="text" name="sales_invoice_number">
                                         <input type="submit" value="Confirm"></td>
                                        </form>
                                               <td><?php echo $cart_row['date'];?></td>
                                            <td width="140"><a href="update_status.php<?php echo '?id='.$order_id; ?>" class="btn btn-success"><i class="fa fa-check"></i>&nbsp;Confirm Order</a></td>

                                        </tr>

The problem is in this:

 <form action="update_sir.php" method="get">
                                     <td ><input type="text" name="sales_invoice_number">   <input type="submit" value="Confirm"></td>
                                                </form>`

The Confirm Order button should only be clickable when the sales_invoice_number is updated first but the problem is that I cannot update it using the code above.
Here's my update_sir.php

<?php
include('connect.php');
$sir = $_GET["sales_invoice_number"];
mysql_query("update order_details set sales_invoice_number ='$sir' where orderid='$get_id'")or die(mysql_error());

                 header('location:orders.php');

?>

What seems to be the problem?

Your question and so is your problem not too clear. Please try first to expain what you want to achieve and then explain what is a problem because I personally don't get your question straight.