Ich benutze switch-Anweisungen, um Komma-Werte einzufügen:

<?php
session_start();
include('config1.php');

$category_id    = 1;
$AnswerID       = $_POST['AnswerID'];
$questionid     = $_POST['questionid'];
$timetaken      = $_POST['timetaken'];
$limit          = $_POST['limit'];

echo "$limit";
$bd = "$limit";

switch ($bd) {
    case"1":
        $sql = "INSERT INTO results (id, user_id, category_id, q_id, answer_id, time_taken)
            VALUES (',', '".$_SESSION['id']."', '$category_id', '$questionid', '$AnswerID', '$timetaken')";

        if ($conn->query($sql) === TRUE) {
            echo "New record created successfully";
        } else {
            echo "Error: " . $sql . "<br>" . $conn->error;
        }

        $last_id = mysqli_insert_id($conn);
            echo "Last inserted ID is: " . $last_id;
        // Set session variables
        $_SESSION["last_id"] = "$last_id";
        break;

    case"2":
        quiz_test();
        break;

    case"3":
        quiz_test();
        break;

    case"4":
        quiz_test();
        break;

    case"5":
        quiz_test();
        unset($_SESSION['last_id']);
        break;

    default:
        echo "something is wrong";
}
function quiz_test(){
    $sql = "SELECT q_id, answer_id, time_taken FROM results WHERE id='" . $_SESSION["last_id"] . "'";
    $result = mysqli_query($conn, $sql);
    if (mysqli_num_rows($result) > 0) {
        while($row = mysqli_fetch_assoc($result)) {
            $qid=$rows['q_id'];
            $ans=$rows['answer_id'];
            $time=$rows['time_taken'];
        }
    }
    $conn->query("update results set q_id =('$questionid','$qid'),answer_id = ('$AnswerID','$ans'),time_taken=('$timetaken','$time') where id = '" . $_SESSION["last_id"] . "'");
}
?>

Wenn 1 Werte einfügt und die Einfügungs-ID abruft, wird die Sitzung gestartet.

Case 2 Select, Update-Anweisung funktioniert nicht. Folgende Fehler sind aufgetreten:

Notice: Undefined variable: conn in C:\xampp\htdocs\N\exam\exam\DOCS\Insert.php on line 62

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\N\exam\exam\DOCS\Insert.php on line 62

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, null given in C:\xampp\htdocs\N\exam\exam\DOCS\Insert.php on line 63

Notice: Undefined variable: conn in C:\xampp\htdocs\N\exam\exam\DOCS\Insert.php on line 70

Fatal error: Call to a member function query() on a non-object in C:\xampp\htdocs\N\exam\exam\DOCS\Insert.php on line 70