How to get value of unselected checkboxes?

I have checkboxes on my Update-Page. Some of them get selected if the value in database is and the others not. I want to do an update so to check or uncheck the other checkboxes. If the checkbox is selected than it should be executed a sql insert query. The other checkboxes that are not selected, the values of them should be deleted from database.

So how can I get the values of checkboxes that are not selected?

<?php
$query="select description from doors
                    where id_doors IN
                    (select doors_id_doors from access_rights where  users_rfidcode='".$result['rfidcode']."'); ";
               $resultt=$conn->query($query);

                    $SW1_checked='';
                    $SW2_checked='';
                    $SW3_checked='';
                    $PR1_checked='';
                    $PR2_checked='';
                    $PR3_checked='';
                    $HW1_checked='';
                    $HW2_checked='';
                    $HW3_checked='';
                    $ELAB_checked='';
                    $CLAB_checked='';
                    $SLAB_checked='';

               while($row=$resultt->fetch_assoc()){

                    if($row['description'] =="SW1") {
                    $SW1_checked='checked';}

                    if($row['description'] =="SW2") {
                    $SW2_checked='checked';}

                    if($row['description'] =="SW3") {
                    $SW3_checked='checked';} 

                    if($row['description'] =="PR1") {
                    $PR1_checked='checked';}

                    if($row['description'] =="PR2") {
                    $PR2_checked='checked'; } 

                    if($row['description'] =="PR3") {
                    $PR3_checked='checked'; } 

                    if($row['description'] =="HW1") {
                    $HW1_checked='checked'; } 

                    if($row['description'] =="HW2") {
                    $HW2_checked='checked'; } 

                    if($row['description'] =="HW3") {
                    $HW3_checked='checked'; }

                    if($row['description'] =="ELAB") {
                    $ELAB_checked='checked'; }  

                    if($row['description'] =="CLAB") {
                    $CLAB_checked='checked'; } 

                    if($row['description'] =="SLAB") {
                    $SLAB_checked='checked'; } 
               }
               echo '<input id="sw1" class="check" type="checkbox" name="chk[]" value="SW1"'.$SW1_checked.' >SW1 &nbsp;&nbsp;';
               echo " <input id='sw1h' type='hidden' name='chk[]'>";
               echo '<input id="sw2" class="check" type="checkbox" name="chk[]" value="SW2"'.$SW2_checked.' >SW2 &nbsp;&nbsp;'; 
               echo " <input id='sw2h' type='hidden' name='chk[]'>";                  
               echo '<input id="sw3" class="check" type="checkbox" name="chk[]" value="SW3"'.$SW3_checked.' >SW3 &nbsp;&nbsp;'; 
               echo " <input id='sw3h' type='hidden' name='chk[]'>";
               echo '<input class="check" type="checkbox" name="chk[]" value="PR1"'.$PR1_checked.' >PR1 &nbsp;&nbsp;&nbsp;';    
               echo '<input class="check" type="checkbox" name="chk[]" value="PR2"'.$PR2_checked.' >PR2 &nbsp;&nbsp;&nbsp;<br>';                   
               echo '<input class="check" type="checkbox" name="chk[]" value="PR3"'.$PR3_checked.' > PR3 &nbsp;&nbsp;&nbsp;';
               echo '<input class="check" type="checkbox" name="chk[]" value="HW1"'.$HW1_checked.'> HW1 &nbsp;&nbsp;';
               echo '<input class="check" type="checkbox" name="chk[]" value="HW2"'.$HW2_checked.'> HW2 &nbsp;&nbsp;';
               echo '<input class="check" type="checkbox" name="chk[]" value="HW3"'.$HW3_checked.' > HW3 &nbsp;&nbsp;<br>';
               echo '<input class="check" type="checkbox" name="chk[]" value="ELAB"'.$ELAB_checked.'  > ELAB &nbsp;';
               echo '<input class="check" type="checkbox" name="chk[]" value="CLAB"'.$CLAB_checked.' > CLAB &nbsp;';
               echo '<input class="check" type="checkbox" name="chk[]" value="SLAB"'.$SLAB_checked.' > SLAB &nbsp;';
                ?>