Display database fields with some conditions

Question

I want to display the invoice bill for each customer when admin clicks on view bill button for that customer. Also I want to display all the newspaper details in a single invoice when customer name is same.I have included the relevant code and database snapshots.

c_details.php

<?php
session_start();
include_once("connect.php");
$query="SELECT * FROM  sub_details";
$result=mysqli_query($conn,$query);
?>



<table align="center">     
    <h3 style="color: black; font-weight: bold; text-align: center;"> 
    Subscription details</h3><br>
    <tr>            
      <th style="text-align: center;">Id</th>
      <th style="text-align: center;">Name</th>
      <th style="text-align: center; width: 900px">Newspaper</th>
      <th style="text-align: center;">Duration</th>
      <th style="text-align: center;">Price</th>
      <th style="text-align: center; width: 800px">Subscription date</th>
      <th style="text-align: center;">Remaining Days</th>
      <th style="text-align: center;">Bill</th>
    </tr>
    <?php while($rows=mysqli_fetch_assoc($result)) {
      ?>


      <tr>
        <td><?php echo $rows['id']; ?></td>
        <td><?php echo $rows['name']; ?></td>
        <td><?php echo $rows['newspaper']; ?></td>
        <td><?php echo $rows['duration']; ?></td>
        <td><?php echo $rows['price']; ?></td>
        <td><?php echo $rows['sdate']; ?></td>
        <?php  echo var_dump($result->fetch_all(MYSQLI_ASSOC));
        $date1=date_create();
        $date2=date_create($rows['edate']);
        $interval=date_diff($date2,$date1)->format("%a days");
         ?>
         <td><?php echo $interval; ?></td>
         <td>
     <form action="invoice.php" method="GET">   
     <?php $invoiceId = $rows['name']; ?>  
   <button type="submit" onclick= "window.open('invoice.php?name= '<?php echo  
   $rows['name']; ?>)" class="btn btn-primary btn-lg" value="submit" >
   View bill</button></td>
      </form>                                                               
      </tr>
      <?php } ?>
   </table>

invoice.php

<?php
include_once("connect.php");   
$invoiceId = isset($_GET['name']) ? $_GET['name'] : null;
if($invoiceId) {
    $query = "SELECT * FROM  sub_details WHERE name = ? limit 1";
    $result = mysqli_query($conn,$query);
?>  

    <?php while($rows=mysqli_fetch_assoc($result)) {
              ?>
         <form style="text-align: left;margin-left: 30px" class="register-form" id="register-form">
        <div class="form-group"> Bill no: &nbsp;&nbsp;&nbsp;&nbsp; <input type="text" name="id" value="<?php echo $rows['id']; ?>"></div><br>
        <div class="form-group">Name:  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <input type="text" name="name" value="<?php echo $rows['name']; ?>"></div><br>
        <div class="form-group">Address: &nbsp; <input type="text" name="address" value="<?php echo $rows['address']; ?>"></div><br><br>
        </form>
         </th>
         </tr>

         <td>
         <table cellpadding="5px" cellspacing="6px" style="width: 75%; border-radius:20px;">
         <tr>
            <th>Newspaper</th>
            <th >Duration</th>  
            <th >Price</th>             
         </tr>

        <tr>
            <td ><?php echo $rows['newspaper']; ?></td>
            <td><?php echo $rows['duration']; ?></td>       
            <td><?php echo $rows['price']; ?></td>

        </tr>

        <tr>
            <td>DELIVERY CHARGES</td>
            <td colspan="3" style="padding-right:60px;text-align: right;">50</td>
        </tr>

        <tr>
            <th>Total</th>         
             <?php
             $t_price=$rows['price']+ 50; ?>
         <th colspan="3" style="text-align: right;padding-right: 55px"><?php echo $t_price; ?></th>
        </tr>

        <tr>
            <th colspan="4" >
                <br><br><br><br><br><br><br>

            </th>
        </tr>
        </table>
        </td>   


         <tr>
            <th colspan="4" style="border-top-color: #ffff4d">
        <p style="text-align: left;">Note: Clients are requested to pay the bill before 5th of every month.</p> 
            </th>
          </tr>
          <?php } ?>
        </table>

Database screenshots

Answer 1

First, you should pass the invoice ID for each record in c_details.php so that you can identify them later:

<button type="submit" onclick= "window.open('invoice.php?id='<?php echo $rows['id']; ?>)" class="btn btn-primary btn-lg" value="submit" >View bill</button>

It will produce URLs like invoice.php?id=<id>, where <id> is the ID for each record in the database. So, for example, a record with the ID 102 will be invoice.php?id=102.

On invoice.php, you can retrieve the ID with $_GET['id']. You should adjust your query to fetch the data for the given invoice:

$invoiceId = isset($_GET['id']) ? $_GET['id'] : null;
if($invoiceId) {
    $query = $conn->prepare("SELECT * FROM sub_details, signup_c WHERE id = ? limit 1";
    $query->bind_param('s', $invoiceId);
    $query->execute();
    $result = $query->get_result();
}

If you're using PHP 7.0 or later, you can simplify your code using the null coalescing operator:

$invoiceId = $_GET['id'] ?? null;

I strongly recommend you to learn about how to prevent SQL injections in PHP.