Dreaming of a voting program written by myself

<?php
Ob_start ();
Session_Start ();
Require_once ("config.php");
?>

<!---form section
Click to vote
<form name= "frm" action= "{dede:global.cfg_cmsurl/}/toupiao/index.php" method= "POST" >
<input type= "hidden" name= "ITM" value= "{Dede:field.aid/}" >
<input type= "Submit" value= "vote"/>
</form>

-
<a href= "Javascript:history.go (-1);" > Up one page </a>
<?php
Print_r ($_post);

if (@$_post["ITM"]) {

if (@$_session["vote"]==session_id ())
{
?>
<script language= "JavaScript" >
Alert ("You have voted");
Location.href= "Javascript:history.go (-1);";
</script>
<?php
Exit ();
}

$id =$_post["ITM"];
$sql = "Update dede_addon17 set num=num+1 where aid= $id";
if (mysql_query ($sql))
{
$_session["Vote"]=session_id ();
?>
<script language= "JavaScript" >alert ("vote succeeded"); location.href= "Javascript:history.go (-1);"; </script>
<?php
}
Else
{
?>
<script language= "JavaScript" >alert ("voting failed"); location.href= "Javascript:history.go (-1);"; </script>
<?php
}
}
?>

Dreaming of a voting program written by myself