Backfilling clicks for downloaded files_PHP Tutorial

The
table of the mysql database table named book is required to contain the following fields:
id Unique identification of the downloaded file
downnum Number of clicks

first.php
{
?>





click here download




ddload.php
include("data.inc.php");
if($incerror)
{
echo $incerror;
exit;
}
if(empty($dnnum)) $dnnum = 1;
else $dnnum ++;
$sql = "update book set downnum ='$dnnum' where id =$id";
mysql_query($sql);
mysql_close($connect);
header(" location:$purl");
?>