invoice.php

    <?php

        session_start();

        include('connect.php');
        require('vendor/autoload.php');

        $order_id = $_GET['order_id'];

        $html = '    <div class="myaccount-table table-responsive text-center">
        <table class="table table-bordered">
            <thead class="thead-light">
                <tr>
                    <th>Order ID</th>
                    <th>Product ID</th>
                    <th>Quantity</th>                                            
                    <th>Price</th>                                            
                    <th>Pay mode</th>
                    <th>Order date</th>  
                                                            
                </tr>
            </thead>
            <tbody>';
            $query = "SELECT * from order_items WHERE email = '".$_SESSION['email']."' AND order_id = '".$order_id."'";
            $grand_total = 0;
                $result = mysqli_query($connect,$query);
                    while($row=mysqli_fetch_array($result)){
                        $productid = $row['product_id'];
                         $grand_total = $row['grand_total'];

                $ccc = "SELECT name from products WHERE id='".$productid."'";
                   $ddd = mysqli_query($connect,$ccc);
                     while($row1 = mysqli_fetch_assoc($ddd)){
                        $proname = $row1["name"];  
                   }        

                $html.='<tr>
                    <td>'.$row['order_id'].'</td>
                    <td>'.$proname.'</td>
                    <td>'.$row['qty'].'</td>
                    <td>'.$row['price']*$row['qty'].'</td>
                    <td>'.$row['pmode'].'</td>
                    <td>'.$row['order_on'].'</td>
                    
                </tr>';
                    }
            $html.='<tr> <td>Grand total is:- '.$grand_total.'</td></tr>';              
            $html.='</tbody>
        </table>
    </div>';

        $mpdf=new \Mpdf\Mpdf();
        $mpdf->WriteHTML($html);
        $file=time().'.pdf';
        $mpdf->output($file,'D');

    ?>

    <link rel="stylesheet" href="assets/css/bootstrap.min.css" />
    <link rel="stylesheet" href="assets/css/style.min.css" />