$uservalid = mysql_query("SELECT `username` FROM `users`",$db);
              while($uservalidarr = mysql_fetch_assoc($uservalid)){
                  $searcharray = in_array($_POST['username'], $uservalidarr);
                  if($searcharray) {
                      $userisvalid = TRUE;
                  }
                  else {
                      $userisvalid = FALSE; //need to fix
                      break;
                  }
              }
                     if($userisvalid == TRUE){
                      echo "the username you chose is already in use! please pick another one. <a href="reg.php">try again</a>";
                      die();
                  } else {
                      $result  = mysql_query("insert into `users` (username,password) values('"
                      . $username . "','" . $password   . "')", $db);
                    if(mysql_affected_rows($db) != 1){ //check if you filled a row in the table "users" in the mysql
                            echo "can't save your registration <br> please try to fill it again";
                            die();
                    }
                    echo "you have succecfully registered! please <a href="login">login</a> to the website!";