php 广告点击统计代码(php+mysql)

$ad_select="select ad_id,ad_url from ad_count where ad_id='$ad_id' limit 1";
$ad_update="Update ad_count set ad_hit=ad_hit+1 where ad_id='$ad_id' limit 1";

$ad_result=mysql_query($ad_select) or die('id error');

if( mysql_num_rows( $ad_result) ){
mysql_query($ad_update);
$ad_rs=mysql_fetch_array($ad_result);
header("location:".$ad_rs['ad_url']);
mysql_free_result($ad_rs);
}
}

function htmltohtml($Str){
$temp =str_replace(chr(13),'
',$Str);
$temp =str_replace('<','<',$Str);
$temp =str_replace('>','>',$Str);
$temp =addslashes($Str);
return $temp;
}
function get_value($value,$para){
return htmltohtml(empty($para)?(isset($_GET[$value])?$_GET[$value]:''):(isset($_POST[$value])?$_POST[$value]:''));
}