Incrementing PHP variable value by 1 whenever user click submit button

Question

I'm trying this code to increment the complete flag by 1 whenever user click on complete button. I have tried some workarounds but nothing's working.

This is the script which is basically printing the details of students room from a table and looks like this:

Room | LastChecked | Checks this Week | time | AssignedTo

123 | March 14, 22 | 1 | 8.50AM | test123 | |CompleteButton|

The supervisor has to click on complete button to confirm the room checkout.

Script:

<div id="tabs_sections_2">

                <p></p>

                <?php
                $rooms = array_filter($roomInspection, function ($v) {
                    return $v["Agent"] != 'N/A' and $v["CompletedBy"] == "";
                });

                echo '<table class="sortable" width="100%">';
                echo '<tr><th>Room</th><th>Last Checked</th><th>Checks this week</th><th>Time</th><th>Assigned To</th></tr>';
                foreach ($rooms as $room) {

                    //echo '<tr><td align="left">' . $room['Room'] . '</td><td>' . date('Y-m-d h:i a', strtotime($room['LastChecked'])) . '</td><td>' . $room['WeekChecks'] . '</td>' . '<td>' . date('Y-m-d h:i a', strtotime($room['Time'])) . '</td>' . '<td>' . $room['Agent'] . '</td><td>' . '<button class="buttonBlack complete" type="submit" '<a href="Test.html?ID=' . $i . '"onclick="$(\'#roomId\').val(' . '\'' . $room['Room'] . '\'' . '); $(\'#weekChecks\').val(' . '\'' . $room['WeekChecks'] . '\'' . '); $(\'#id\').val(' . '\'' . $room['Id'] . '\'' . ')";><i class="fas fa-check fa-1x complete"></i> Complete</button>' . '</td>';
                    
                    $var = $room['sysId'];
                    $url = 'https://abctest.com/nav_to.do?uri=x_ttuit_cts_checks_cts_checks.do?sys_id=-1%26sysparm_query=u_room_number=' . $var;

                    
                    echo '<tr><td align="left">' . $room['Room'] . '</td><td>' . date('Y-m-d h:i a', strtotime($room['LastChecked'])) . '</td><td>' . $room['WeekChecks'] . '</td>' . '<td>' . date('Y-m-d h:i a', strtotime($room['Time'])) . '</td>' . '<td>' . $room['Agent'] . '</td><td>' . '<a href ='.$url.' target= "_blank"'.'><button class="buttonBlack complete" name="submit" type="submit" onclick="update(\'' .$room['CompleteStatus']. '\')"
                   ><i class="fas fa-check fa-1x complete"></i> Complete</button></a>' . '</td>';
                    


                echo '</table><br><br>';

                if ($workday == false) {
                    echo "<p align='center'><i>No student is scheduled for work today</i></p>";
                }

                ?>
            </div>

The value of room['CompleteStatus'] has already been defined 0 for all the rooms.

I'm not sure what to put in update() javascript function to increment this variable value.