下载文件的点击数回填

需要名称为book的mysql数据库表
表中含有下列字段：
id 下载的文件的唯一标识
downnum 点击数

first.php
<?while($myrow = @mysql_fetch_array($result))
{
?>
<TR>
<TD>
<?if(empty($myrow["downnum"])) echo "0"; else echo $myrow["downnum"]; ?>
</TD>
<TD>
<a href="ddload.php?purl=downfileurl&dnnum=<?echo $myrow['downnum'] ?>&id=<?echo $myrow['id']?>">click here download </a>
</TD>
</TR>
<?};?>

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"); 网管u家u.bitsCN.com
?>