unable to open modal pop up window

@kvanaraj,

The error is straight forward.  What value is $book['appno'] returning?  Does your modal id have the same name?

foreach($books as $book){
        
          ?>
     <tr>
              
             <?php   echo '<td align="center">'.$sno++.'</td>';?>
                <td><?php echo $book['dai'];?></td>
                <td><?php echo $book['appno'];?></td>
<td>
<button class="btn btn-warning" onclick="edit_book(<?php echo $book['appno'];?>)"><i class="glyphicon glyphicon-pencil"></i></button>



</td>