random question in game

i am working in a game that can display a random question to user ,all work is going well,but the problem is that there is a probability that a same user can get the same question at same session,i dont want it, here is my code

$runs     = $_REQUEST['runs'];
$query    = "SELECT max开发者_Python百科(id) FROM question$runs";
$result1  = db_execute($query);
$ans      = mysql_fetch_array($result1);
$max      = $ans['0'];
$rand_no  = mt_rand(0,$max);
$query1   = "SELECT * FROM question$runs WHERE id='$rand_no'";

now how can i avoid the same question from a same user at same session any idea?plz share thanQ all

create an array with previous question ids and store it into $_SESSION. When generating new random number check if its already there. If so regenerate random number

As Voooza said, store asked questions in the session. Something like this should do the trick:

session_start();
$runs     = $_REQUEST['runs'];
$query    = "SELECT max(id) FROM question$runs";
$result1  = db_execute($query);
$ans      = mysql_fetch_array($result1);
$max      = $ans['0'];
$valid_question = false;
while (!$valid_question) {
    $rand_no = mt_rand(0,$max);
    if (!in_array($rand_no, $_SESSION['questions'])) {
        $valid_question = true;
    }
}
$_SESSION['questions'][] = $rand_no;
$query1   = "SELECT * FROM question$runs WHERE id='$rand_no'";

Have a data structure that contains the questions asked during a particular question. Add new questions to that container every time you create one; check the container each time to make sure that the new question doesn't appear. If it does, look for another one.

If memory is an issue and you cannot store every question answered by every active session, you could just store a single random seed with each session, and the # of questions answered. For each question answered, use a shuffle algorithm (i.e. random permutation) and return the next item in the sequence.

[update]

Another option is... IF you don't mind everyone having the same order of questions, then just assign a random number to each question and return them in sequence, ordered by the random number.

i think there is no need of session here.

function avoid_random_repeat($r)
     $rand           = mt_rand(0,$max);
     $unique         = avoid_random_repeat($rand);

   if(in_array($r,$testing)){
      $rand_no  = mt_rand(0,$max);
      avoid_random_repeat($rand_no);
      }
     else{
   array_push($testing,$r);
     return;
      }
  }