vote coding php

<?php
//////////////////////////////
session_start();
$s_id=session_id();

if(!isset($_POST[opt])){echo "<font face='Verdana' size='2' color=red>Please select one option and then submit</font>";}
else{

//ADDED by PusHm0v....

$ip_address = $_SERVER['REMOTE_ADDR'];
//cek ke tabel ip_vote...
$qry=mysql_query("select ip_address from ip_vote where ip='$ip_address'"); 
// mysql_num_rows akan menghasilkan JUMLAH row/baris dari database yg cocok dengan kriteria WHERE... dalam hal ini mencari ip address yang udah ter record ke database.
if (mysql_num_rows($qry)) 
{
  echo "IP ADDRESS udah ngelakuin vote...";
  exit();
}
//kalo gak ada di database baru masukin voting, n jgn lupa INSERT ip address ke tabel ip_vote...
$qry=mysql_query("INSERT INTO ip_vote(ip) VALUES ('$ip_address')"); 

//DONE ADDED by PusHm0v...

//ambil data vote yang di pilih
//cek berapa jmlh votenya 
$qry=mysql_query("select vote from data_polling where pilihan='$_POST[opt]'");
$hsl=mysql_fetch_array($qry);
$jvot=$hsl[vote];

//jmlvote=hasilvote+1
$jmlvote=$jvot+1;

mysql_query("update data_polling set vote='$jmlvote' where pilihan = '$_POST[opt]'");

values('$s_id',$qst_id,'$opt')");

echo mysql_error();
echo "Thanks for your views, Please <a href=view_poll_result.php>click here to view the poll result</a> or click here to visit the <a href=poll_display.php>VIEW PAGE</a>";

}
?>