为什么$up只能到1
$up=0;
while(@$_GET['action']=='up'){

$up++;
$up_sql="update message set up='$up' where id=$_GET[id]";
if(mysql_query($up_sql)){
echo $up;
exit('<script language="javascript">alert("成功！");self.location = "admin.php";</script>');
}
}

[解决办法]
$up_sql="update message set up=up+1 where id=$_GET[id]";