i need to update quantity separately, but when i update it updates all of the quantities

Question

<tr align="center">
    <td>
        <input type="checkbox" name="remove[]" value="<?php echo $pro_id;?>">//removes checked items  
    </td>
    <td>
      <img src="admin_area/product_images/<?php echo $product_image?>" width="60" height="60"/><br>//displays products image
      <?php echo $product_title ?>//displays products title
  </td>
  <td>
      <input type="text" size="4" name="qty" value="<?php echo $_SESSION["qty"]; ?>"><span style="color:red">Required</span>
  </td>//textbox where user enters the new quantity
  <input type="hidden" name="pro_id" value="<?php echo $pro_id; ?>">
</td>
<?php
$sql = "select * from cart";
$run_query = mysqli_query($con,$sql);
while ($row = mysqli_fetch_array($run_query)) {
    $_SESSION["qty"] = $row['qty'];
}

if (isset($_POST['update_cart'])) {
    $ip = getIp();
    $Updateqty = $_POST['qty'];
    //get quantity from the text boxes which are repeated with every product

    $pro_id = $_POST['pro_id'];
    //gets the id from the hidden field

    $update_qty = "UPDATE cart SET qty='$Updateqty' where p_id='$pro_id' and ip_add='$ip'";
    $run_qty = mysqli_query($con, $update_qty);

    if ($run_qty) {
        echo"<script>window.open('cart.php','_self')</script>";
    }
}
?>
</tr>

Answer 1

There's a problem here:

$sql = "select * from cart";
$run_query = mysqli_query($con,$sql);
while ($row = mysqli_fetch_array($run_query)) {
    $_SESSION["qty"] = $row['qty'];
}

This while loop will overwrite $_SESSION["qty"] with each iteration, so it will always be set to the quantity of the last item in the cart.

Then that session value is used in the display for each item.

<input type="text" size="4" name="qty" value="<?php echo $_SESSION["qty"]; ?>"><span style="color:red">Required</span>

Also, if what you've shown in your question is one row from a table that has multiple rows, and you have wrapped the entire table in one form, every input will be submitted, and since you have multiple values for qty and pro_id, only the last one will be used. This is what is making it look like every quantity is being updated.

---

I would suggest an approach like this to get it working. This may not work for you as-is, because I guessed on some of the names, but should be enough to show what I have in mind:

<?php

if (isset($_POST['update_cart'])) {
    $ip = getIp();

    // prepare an update statement
    $sql = "UPDATE cart SET qty=? where p_id=? and ip_add=?";
    $stmt = mysqli_prepare($con, $sql);

    // loop over each quantity and update
    foreach ($_POST['qty'] as $pro_id => $qty) {
        $stmt->bind_param("iis", $qty, $pro_id, $ip);
        $stmt->execute();
    }
}

$sql = "select * from cart";
$run_query = mysqli_query($con,$sql);
while ($row = mysqli_fetch_array($run_query)) {
    // update the session with the new values
    $_SESSION[$row['p_id']]['qty'] = $row['qty'];
}

?>

That should update quantity for each item, but it depends on an array of qty values being provided by your form. In order to have that, you need to name your inputs using an array syntax like this:

<form action="" method="post">
    <table>
        <?php foreach ($products as $product): ?>
        <tr>
            <td>Other product info</td>
            <td>
                <input type="text" 
                    name="qty[<?php echo $product['id'] ?>]"
                    value="<?php echo $_SESSION[$product['id']]['qty']; ?>">
            </td>
        </tr>            
        <?php endforeach ?>
    </table>
    <input type="submit" name="update_cart" value="Update Cart">
</form>