if(isset($_GET['id']) && !empty($_GET['id'])) {
  $id = $_GET['id'];

  $q = mysql_query("SELECT * FROM `reklam` WHERE `id` = '$id'");

  if($q && mysql_num_rows($q) > 0) {
    $row = mysql_fetch_assoc($q);

    mysql_query("UPDATE `reklam` SET `tiklama` = `tiklama` + 1 WHERE `id` = '$id'");

    header('location: ' . !empty($row['link']) ? $row['link'] : 'http://sizinsiteniz.com/');
  }
  else {
    header('location: ' . !empty($row['link']) ? $row['link'] : 'http://sizinsiteniz.com/');
}
else {
  // hata
}