php - How to Update Mysql Data with a button on Home Page that is passing id on URL?

I have created an Edit Item popup Bootstrap modal on home page. Now what I want is to update the selected item details using the PHP.

Here i am passing item id through the URL in order to select the item

Now when I press edit Button it opens a Popup with all the details in it( already filled) but when I try to click on Save Changes Button it just do nothing and My data not updated. I have also used POST method but its not working.

Here is the Button that opens the Popup Modal

<?php 
$res= mysqli_query($db,"SELECT* FROM `books`;");

if(mysqli_num_rows($res)>0){
  while($row= mysqli_fetch_assoc($res)){
    if($row!=0)
    {
    $bid= $row['book_id'];
 ?>
<ul>
<li>
 <a onclick="$('#editModal<?php echo $row['book_id']?>').modal('show');" class="btn-show-modal edit-btn" data-toggle="modal"><i style="padding-right: 140px;" class="fas fa-edit"></i></a>
</li>


<!--Here is the Popup Modal for Edit -->

<div id="editModal<?php echo $row['book_id']?>" class="modal fade" tabindex="-1" role="dialog">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">Edit This Book</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <form action="updatebook.php" method="POST">
          <div class="form-group">
            <label for="isbn" class="col-form-label">ISBN</label>
            <input type="text" class="form-control" name="isbn" value="<?php echo $row['isbn'];?>">
          </div>
          <div class="form-group">
            <label for="title" class="col-form-label">Enter Book Title</label>
            <input type="text" class="form-control" name="title" value="<?php echo $row['title'];?>">
          </div>
            <div class="form-group">
            <label for="author" class="col-form-label">Enter Author Name</label>
            <input type="text" class="form-control" name="author" value="<?php echo $row['author'];?>">
          </div>
            <div class="form-group">
            <label for="image" class="col-form-label">Image URL</label>
            <input type="text" class="form-control" name="image" value="<?php echo $row['image'];?>">
          </div>
            <div class="form-group">
            <label for="description" class="col-form-label">Enter Book Description</label>
            <textarea class="form-control" name="description" value="<?php echo $row['description'];?>"></textarea>
          </div>
            <div class="form-group">
            <label for="url" class="col-form-label">Book URL</label>
            <input type="text" class="form-control" name="url" value="<?php echo $row['url'];?>"></textarea>
          </div>
        </form>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <a href="updatebook.php?id=<?php echo $row['book_id']?>"><button type="button" class="btn btn-primary" name="save">Save Changes</button></a>
      </div>
    </div>
  </div>
</div>


<?php 
}
}
}

else
{
   echo"<h1 style='color: white;font-size:58px; font-family: Poppins; font-weight: 600;' class=m-2>U!Oh Nothing Found Here!</h1>
<button onclick=\"window.location.href='add_books_form.php'\" class=\"btn btn-info bg-primary m-5\">Contribute</button>";
 }
?>

</ul>
Copy code

Here is the updatebook.php Page

<?php

include "connection.inc.php";

if(isset($_POST['save']))
{
    $id= $_POST['id'];
    $isbn= $_POST['isbn'];
    $title= $_POST['title'];
    $author= $_POST['author'];
    $image= $_POST['image'];
    $desc= $_POST['description'];
    $url= $_POST['url'];

$res = mysqli_query($db, "UPDATE books SET isbn= '$isbn', title= '$title', author= '$author',image= '$image', description= '$desc', url= '$url' WHERE book_id= '$id'");
?>
if($res) 
{
    <script type="text/javascript"> 
        alert("Data Updated Successfully"); 
        window.location.href= "home.php";
    </script>
}
else
{
    <script>
    alert("Not Updated!");
        window.location.href="home.php";
    </script>
}
<?php
}
?>

Copy code

Please Help me to solve this Update Issue i am facing for a long time. I have researched all through but didn't got any solution.