stop people from hacking with unset

[Monkuar]

if ($indovina!=$indovinata) {
if ($tentativi>=6) {
  echo ("\n<p>Sorry, you hanged yourself. The word you had to guess was: ".$indovina."</p>\n");
}
else {
  $scelt = preg_split('//', $scelte, -1, PREG_SPLIT_NO_EMPTY);
  echo ("\n<p>\n");
  foreach ($alfabeto as $lettalf) {
   $contrl = false;
   foreach ($scelt as $lett) {
    if (!strcasecmp ($lettalf, $lett)) {
     $contrl = true;
    }
   }
   if ($contrl) {
    print (' <img src="images/lr_'.$lettalf.'.gif" style="border:0;width:20px;height:20px" alt="'.$lettalf.'" />');
   }
   else {
    print (' <a href="'.$_SERVER['PHP_SELF'].'?letter='.$lettalf.'"><img src="images/lb_'.$lettalf.'.gif" style="border:0;width:20px;height:20px" alt="'.$lettalf.'" /></a>');
   }
   if ($lettalf=='m') echo ("\n <br />");
   echo ("\n");
  }
  echo ("</p>\n"); 
}
}
else if ($indovinata){
echo ("\n<p>Congratulations! You guessed the word.</p>\n");
$DB->query("UPDATE ibf_members set gold=gold+5
			WHERE id = {$ibforums->member['id']}");
}

 

 

Look at the bottom, ok so if the person wins the hangman game, it will show "Congrats" but then people will just beable to refresh the page, and that query will run again and again and that person will gain +5 gold each time....we need to fix this!! any help?

[PFMaBiSmAd]

You should remember which letters have already been used and output a message if the same one is selected again or someone refreshes the page and submits the same letter again.