Güvenlik açıkları

<?
function guvenlik($q) {  
    $q = htmlspecialchars(stripslashes($q)); 
    $q = str_replace("script", "blocked", $q); 
    $q = str_replace("select", "", $q); 
    $q = str_replace("SELECT", "", $q); 
    $q = str_replace("UPDATE", "", $q); 
    $q = str_replace("update", "", $q); 
    $q = str_replace("delete", "", $q); 
    $q = str_replace("DELETE", "", $q); 
    $q = str_replace("UNION", "", $q); 
    $q = str_replace("union", "", $q); 
    $q = str_replace('"', "", $q); 
    $q = str_replace("%", "", $q); 
    $q = mysql_escape_string($q); 
    $q = str_replace("`","",$q); 
    $q = str_replace("'","'",$q); 
    $q = str_replace("-","-",$q); 
    $q = str_replace("&","",$q); 
    $q = str_replace("%","",$q); 
    $q = str_replace("<","",$q); 
    $q = str_replace(">","",$q); 
    $q = trim($q); 
    return $q;  
}
?>

$Ad_Soyad = guvenlik($_POST["Ad_Soyad"]);