While loop updation value - php

Question

I am developing online attendance.But I stuck in while loop condition
I want to show my code first
<tbody>
<?php
$database = new Database();
$db = $database->getConnection();
$user = new User($db);
$stmt = $user->atten();
while($ro22 = $stmt->fetch(PDO::FETCH_ASSOC))
{
?>
<tr>
<td><input name ="uname" id ="uname" onBlur="checkAvailability2()" style ="border:none" value = "<?php echo $ro22['user_id'] ?>"/></td>
<td><?php echo $ro22['first_name'] ?> <?php echo $ro22['last_name'] ?></td>
<td><?php echo $ro22['parent_contact'] ?></td>
<td><input type="button" value="<?php echo $ro22['ai'] ?>" id="pres" name="pres" onclick="return change(this);" onBlur="checkAvailability()" class="w3-button w3-teal"/></td>
</tr>
<?php } ?>
</tbody>
This is output
What I want
I want update present,absent value based on 101,102,103... value
I tried many but failed. Please help me out
Thanks in advance

Answer 1

You need to place a call to the page on a click and pass the user_id. This is easy to do with jQuery:
function change(row) {
$.post('thispage.php', { user_id: $(row).val() }, function(){ window.location.reload(); } );
}
And then receive the post in the PHP:
if (!empty($_POST['user_id'])) {
/* toggle admission status */
}
After the request completes and the status is toggled, the page will reload.

Answer 2

Here is a general example. It's consisted of your PHP program (the AJAX sender) which I rewrote to be they way I think you wanted, a javascript file (containing the AJAX function) and another PHP file (the AJAX request receiver).
You can get different use-cases by altering the database query in the receiving PHP file.
Javascript file (AJAX):
// Send the `id` of the element
function checkAvailability(id)
{
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function()
{
// This `if` underneath is success. It means we got a response back
if (this.readyState == 4 && this.status == 200)
{
if(this.responseText == "OK")
{
alert('ID: ' + id + ' changed. Response: ' + this.responseText);
document.getElementById("demo").innerHTML = 'The student has been updated.';
}
else if(this.responseText == "Not OK")
{
alert('Something went wrong with id: ' + id);
}
}
};
// For example you send a request to attendance.php sending `id` info
// - attendance.php just needs to echo the response to answer back
xhttp.open("GET", "attendance.php?id=" + id, true);
xhttp.send();
}
Main PHP page (the file that sends the request):
// U need jQuery to be able to send AJAX requests. Copy this, add to your html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<?php
$database = new Database();
$db = $database->getConnection();
$user = new User($db);
$stmt = $user->atten();
echo '<table>
<tr>
<th>Student ID</th>
<th>Student name</th>
<th>Phone number</th>
<th>Today\'s attendance</th>
</tr>';
while($ro22 = $stmt->fetch(PDO::FETCH_ASSOC))
{
echo '<tr>
<td><input name ="uname" id ="uname" onBlur="checkAvailability2()" style ="border:none" value="'.$ro22['user_id'].'"/></td>
<td>'.$ro22['first_name'].' '.$ro22['last_name'].'</td>
<td>'.$ro22['parent_contact'].'</td>
<td><input type="button" value="'.$ro22['ai'].'" id="pres" name="pres" onclick="change(this.id);" onBlur="checkAvailability(this.id)" class="w3-button w3-teal"/></td>
</tr>';
}
echo '</table>';
?>
The receiver file:
<?php
$conToDatabase = ... // Here goes DB connection data
if(isset($_GET['id']) && ctype_digit($_GET['id']))
{
$clean['id'] = $_GET['id'];
}
// Query your DB here using variable $clean['id'] as ID
$querySuccess = ...
// if query successful echo 'OK';
// else echo 'Not OK';
?>