สอบถามเกี่ยวกับการเรียกใช้ตัวแปรที่สร้างไว้ ด้วยการ วนลูป

$sqlAD4 = "Select * from zDay";
$queryAD4 = mysql_query($sqlAD4);

<?php $DT = '0' ?> 
           <?php while($showAD4 = mysql_fetch_array($queryAD4)){?>
           <tr>
		   <td align="center" width="105"><?php echo $showAD4['Day'] ?></td>	
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>" value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td> 
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
           <td align="center" width="105"><input type="checkbox" id="<?php $DT ?>"value="1"></td>
           <?php ++$DT ?>
          
           </tr>
            <?php
		   }
		   ?>