I have done my code using photo mysql but I take more than 7 hours in execution please guide me for reduce time

ini_set('max_execution_time', 15000);
ini_set("memory_limit","1028M");

mysql_query('TRUNCATE TABLE scrip_average');

$sql_all = mysql_query("select * From all_scrip limit 8000");
  while($row_all = mysql_fetch_array($sql_all))
  { 

  $SC_CODE=$row_all['SC_CODE'];
  
  $sql_last = mysql_query("select * From scrip where SC_CODE='$SC_CODE' ORDER BY ID DESC  LIMIT 1");
  while($row_last = mysql_fetch_array($sql_last))
  { 
$LAST_OPEN=$row_last['OPEN'];
$LAST_HIGH=$row_last['HIGH'];
$LAST_CLOSE=$row_last['CLOSE'];
$LAST_LOW=$row_last['LOW'];

}

  
 
  for ($n = 200; $n >0; $n--)
{
  $total_OPEN=0;
  $total_HIGH=0;
  $total_LOW=0;
  $total_CLOSE=0;

  $result_open=mysql_query("SELECT SUM(OPEN) AS total_value FROM scrip where SC_CODE='$SC_CODE' ORDER BY ID DESC  LIMIT $n");
$total_OPEN=mysql_result($result_open,0,0);

 $result_high=mysql_query("SELECT SUM(HIGH) AS total_value FROM scrip where SC_CODE='$SC_CODE' ORDER BY ID DESC  LIMIT $n");
  $total_HIGH=mysql_result($result_high,0,0);

 $result_low=mysql_query("SELECT SUM(LOW) AS total_value FROM scrip where SC_CODE='$SC_CODE' ORDER BY ID DESC  LIMIT $n");
 $total_LOW=mysql_result($result_low,0,0);

 $result_close=mysql_query("SELECT SUM(CLOSE) AS total_value FROM scrip where SC_CODE='$SC_CODE' ORDER BY ID DESC  LIMIT $n");
$total_CLOSE=mysql_result($result_close,0,0);

  $total_OPEN=$total_OPEN/$n;
  $total_HIGH=$total_HIGH/$n;
  $total_LOW=$total_LOW/$n;
  $total_CLOSE=$total_CLOSE/$n;
  
$LOW_status='negetive';
if($total_LOW>$LAST_LOW)
{
$LOW_status='possitive';
}
$HIGH_status='negetive';
if($total_HIGH>$LAST_HIGH)
{
$HIGH_status='possitive';
}
$OPEN_status='negetive';
if($total_OPEN>$LAST_OPEN)
{
$OPEN_status='possitive';
}
$CLOSE_status='negetive';
if($total_CLOSE>$LAST_CLOSE)
{
$CLOSE_status='possitive';
}

   $data=array(
   'date'=>$n,
		'SC_CODE'=>$SC_CODE,
		'OPEN'=>$total_OPEN,
		'HIGH'=>$total_HIGH,
		'LOW'=>$total_LOW,
		'CLOSE'=>$total_CLOSE,
		'LOW_status'=>$LOW_status,
		'HIGH_status'=>$HIGH_status,
		'OPEN_status'=>$OPEN_status,
		'CLOSE_status'=>$CLOSE_status);
				//'img_postdate'    =>date("y,m,d"),
	  	$query=insert("scrip_average",$data);	
		


}
}