CODEWITHSUNDEEP
phpdropdown
gellooo
gellooo

Reputation: 35

How to hide selected value in dropdown?

I always got the wrong result every time I choose a value in the select dropdown. I want the process to be like this, after selecting a busnum (bus number), the next dropdown will show the available seat numbers (base on busnum, sched date, and sched time) except for those numbers that are already taken. But every time I run my code, it shows the available seats but it only hides one seat number (taken) when that busnum has multiple taken seats. For example, I select busnum 30, then busnum 30 has already 3 taken seats (1, 3, 9) so if I clicked the next dropdown (for seat numbers), it is supposed to hide 1, 3, 9 out of 15. But it only hides 1 and the 3 and 9 still show. This is my code from that part so far:

 $sel = "SELECT * FROM ticket";
  $rslt = mysqli_query($conn, $sel);
  if($rslt->num_rows>0)
  {
      while($rows = $rslt->fetch_assoc())
      {

    $date = $rows['Tk_Sch_Date'];
    $time = $rows['Tk_Sch_Time'];

    $sel2 = "SELECT * FROM ticket WHERE Bus_Plate_Number='".$_GET['busnum']."' AND Tk_Sch_Date = '".$date."' AND Tk_Sch_Time='".$time."' AND Tk_Stat = 'PAID'";
    $rslt = mysqli_query($conn, $sel2);
    if($rslt->num_rows>0)
    {
      while($data = $rslt->fetch_assoc())
      {
        $chsnseat = $data['Tk_Chsn_Seat'];

        $sel3 = "SELECT * FROM seat WHERE NOT Seat_Num ='".$chsnseat."'";
        $result = mysqli_query($conn, $sel3);
        if($result->num_rows>0)
        {
          while($rows=$result->fetch_assoc())
          {
            ?>
            <option value="<?=$rows['Seat_Num']?>"><?=$rows['Seat_Num']?></option>
            <?php
          }
        }
      }
    }
  }


}
  else
  {
          $sel = "SELECT * FROM seat";
          $result = $conn->query($sel);
          if($result->num_rows>0)
          { 
            while ($rows = $result->fetch_assoc())
            {
              ?>
              <option value="<?php echo $rows['Seat_Num']; ?>"><?php echo $rows['Seat_Num']; ?>
              </option>
              <?php
            }
          }
  }
}

Upvotes: 0

Views: 216

Answers (1)

Barmar
Barmar

Reputation: 780788

You're only filtering out one seat at a time. So on the first iteration you filter out seat 1, but show seats 3 and 9. On the second iteration you filter out 3, but show 1 and 9. And so on.

You need to join the tables so you filter out all the taken seats at once.

$sel2 = "
    SELECT s.*
    FROM seat AS s
    LEFT JOIN ticket AS t ON s.seat_num = t.Tk_Chsn_Seat
        AND Bus_Plate_Number=? AND Tk_Sch_Date = ? AND Tk_Sch_Time= ? AND Tk_Stat = 'PAID'
    WHERE t.Tk_Chsn_Seat IS NULL";
$stmt = $conn->prepare($sel2);
$stmt->bind_param("sss", $_GET['busnum'], $date, $time);
$stmt->execute();
$result = $stmt->get_result();

You also should use prepared statements instead of substituting variables into the SQL, to protect against SQL injection.

Upvotes: 1

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