ช่วยนับถอยหลัง ใน mysql หน่อยครับ นับแบบ เรียว time ครับ

<table class="adminlist">
		<thead>
			<tr>
    <th> <div align="center">ชื่อนาม</div></th>
    <th> <div align="center">ต่ำแหน่ง </div></th>
    <th> <div align="center">หมดอายุอีก </div></th>
    <th> <div align="center">เปิด/ปิด</div></th>
    <th> <div align="center"> </div></th>
  		</tr>
  		</thead>
<?
while($objResult = mysql_fetch_array($objQuery))
{
	$link = $objResult["contit"];
	$link2 = substr($link,0,30);
	
	$dateoff = $objResult["dateoff"];
	$datestart = $objResult["datestart"];	
 
?>
  <tr class="row0">
    <td class="center"><?=$objResult["name"];?></td>
    <td class="center"><center>
    <?php 
	if($objResult["position"] == 1)
	{
		echo "<font color='#b5f441'>ด้านบน</font>";
	}
	elseif ($objResult["position"] == 2) {
		echo "<font color='#ff871a'>ด้านซ้าย</font>";
	}
	elseif ($objResult["position"] == 3) {
		echo "<font color='#8b00ff'>ด้านขวา</font>";
	}
	elseif ($objResult["position"] == 4) {
		echo "<font color='#ff0da6'>ด้านล่าง</font>";
	}
	elseif ($objResult["position"] == 5) {
		echo "<font color='#e60012'>ตรงกลาง</font>";
	}
	?></center>
    </td>
    <td><div id="clock1"></div>
     <script language="JavaScript">

  StartCountDown("clock1","<?=$objResult["dateoff"]; ?>")
  
  /*
  	Author:		Robert Hashemian (http://www.hashemian.com/)
  	Modified by:	Munsifali Rashid (http://www.munit.co.uk/)
  	Modified by:	Tilesh Khatri
  */
  
  function StartCountDown(myDiv,myTargetDate)
  {
    var dthen	= new Date(myTargetDate);
    var dnow	= new Date();
    ddiff		= new Date(dthen-dnow);
    gsecs		= Math.floor(ddiff.valueOf()/1000);
    CountBack(myDiv,gsecs);
  }
  
  function Calcage(secs, num1, num2)
  {
    s = ((Math.floor(secs/num1))%num2).toString();
    if (s.length < 2) 
    {	
      s = "0" + s;
    }
    return (s);
  }
  
  function CountBack(myDiv, secs)
  {
    var DisplayStr;
    var DisplayFormat = "%%D%% วัน %%H%% ชั่วโมง %%M%% นาที %%S%% วินาที";
    DisplayStr = DisplayFormat.replace(/%%D%%/g,	Calcage(secs,86400,100000));
    DisplayStr = DisplayStr.replace(/%%H%%/g,		Calcage(secs,3600,24));
    DisplayStr = DisplayStr.replace(/%%M%%/g,		Calcage(secs,60,60));
    DisplayStr = DisplayStr.replace(/%%S%%/g,		Calcage(secs,1,60));
    if(secs > 0)
    {	
      document.getElementById(myDiv).innerHTML = DisplayStr;
      setTimeout("CountBack('" + myDiv + "'," + (secs-1) + ");", 990);
    }
    else
    {
      document.getElementById(myDiv).innerHTML = "<font color='#FF3300'>หมดเวลาแล้ว</font>";
    }
  }

</script>
    </td>
    <td><center>
    <a href="index.php?op=onoffbanner&onoff=<?=$objResult["id"];?>" title="เปิด/ปิด">
	<?php	  
	if($objResult["onoff"] == 1)
	{
		echo "<div class=\"icon-16-unblock\"></div>";
	}
	elseif ($objResult["onoff"] == 0) {
		echo "<div class=\"icon-16-unpublish\"></div>";
	}
	?></a></center>
    </td>
    <td class="center">
    <a id="edit<?=$i;?>" class="various iframe" href="powerad.php?op=editaddbanner&edit=<?=$objResult["id"];?>"><img src="./img/menu/icon-16-edit.png" width="16" height="16"></a>

&nbsp;<a id="delete<?=$i;?>" class="various iframe" href="powerad.php?op=deletaddbanner&del=<?=$objResult["id"];?>"><img src="./img/menu/icon-16-delete.png" width="16" height="16"></a>
    </td>
  </tr>
<?
}
?>
</table>