SQL INSERT query isn't updating column from a PHP web application - php

Question

I recently modified some code to allow for my quiz.php script to accommodate multiple quizzes as opposed to just one. To do this I sent along the quiz_id and quiz_title variables when the user clicks the link for the quiz and I receive them using $_GET. However, once the quiz form is submitted the quiz_id column no longer updates in the high_score table.
Here is the code for quiz.php
<?php
// Start the session
require_once('startsession.php');
// Insert the Page Header
$page_title = "Quiz Time!";
require_once('header.php');
require_once('connectvars.php');
// Make sure user is logged in
if (!isset($_SESSION['user_id'])) {
echo '<p>Please log in to access this page.</p>';
exit();
}
// Show navigation menu
require_once('navmenu.php');
// Connect to database
$dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
// Declare $quiz_id
$quiz_title = $_GET['title'];
$quiz_id = $_GET['id'];
// print_r($quiz_title);
// print_r($quiz_id);
// Grab list of question_id's for this quiz
$query = "SELECT question_id FROM question WHERE quiz_id = '" . $quiz_id . "'";
$data = mysqli_query($dbc, $query);
$questionIDs = array();
while ($row = mysqli_fetch_array($data)) {
array_push($questionIDs, $row['question_id']);
}
// Create empty responses in 'quiz_response' table
foreach ($questionIDs as $questionID) {
$query = "INSERT INTO quiz_response (user_id, question_id) VALUES ('" . $_SESSION['user_id'] . "', '" . $questionID . "')";
mysqli_query($dbc, $query);
}
// If form is submitted, update choice_id column of quiz_response table
if (isset($_POST['submit'])) {
// Inserting choices into the response table
foreach ($_POST as $choice_id => $choice) {
$query = "UPDATE quiz_response SET choice_id = '$choice', answer_time=NOW() " .
"WHERE response_id = '$choice_id'";
mysqli_query($dbc, $query);
}
// Update the 'is_correct' column
// Pull all is_correct data from question_choice table relating to specific response_id
$total_Qs = 0;
$correct_As = 0;
foreach ($_POST as $choice_id => $choice) {
$query = "SELECT qr.response_id, qr.choice_id, qc.is_correct " .
"FROM quiz_response AS qr " .
"INNER JOIN question_choice AS qc USING (choice_id) " .
"WHERE response_id = '$choice_id'";
$data=mysqli_query($dbc, $query);
// Update is_correct column in quiz_response table
while ($row = mysqli_fetch_array($data, MYSQLI_ASSOC)) {
$total_Qs ++;
if ($row['is_correct'] == 1) {
$query2 = "UPDATE quiz_response SET is_correct = '1' " .
"WHERE response_id = '$row[response_id]'";
mysqli_query($dbc, $query2);
$correct_As ++;
}
}
}
// Update high_score table with $correct_As
$quiz_id = $_POST['quiz_id'];
$query = "INSERT INTO high_score " .
"VALUES ('0', '" . $_SESSION['user_id'] . "', '" . $quiz_id . "', '" . $correct_As . "', NOW())";
mysqli_query($dbc, $query);
// Display score after storing choices in database
echo 'You got ' . $correct_As . ' out of ' . $total_Qs . ' correct';
exit();
mysqli_close($dbc);
}
// Grab the question data from the database to generate the form
$Q_and_Cs = array();
foreach ($questionIDs as $questionID) {
$query = "SELECT qr.response_id AS r_id, qr.question_id, q.question " .
"FROM quiz_response AS qr " .
"INNER JOIN question AS q USING (question_id) " .
"WHERE qr.user_id = '" . $_SESSION['user_id'] . "' " .
"AND qr.question_id = '" . $questionID . "'";
$data = mysqli_query($dbc, $query)
or die("MySQL error: " . mysqli_error($dbc) . "<hr>\nQuery: $query");
// Store in $questions array, then push into $Q_and_Cs array
while ($row = mysqli_fetch_array($data, MYSQL_ASSOC)) {
print_r($row);
$questions = array();
$questions['r_id'] = $row['r_id'];
$questions['question_id'] = $row['question_id'];
$questions['question'] = $row['question'];
// Pull up the choices for each question
$query2 = "SELECT choice_id, choice FROM question_choice " .
"WHERE question_id = '" . $row['question_id'] . "'";
$data2 = mysqli_query($dbc, $query2);
while ($row2 = mysqli_fetch_array($data2, MYSQL_NUM)) {
$questions[] = $row2[0];
$questions[] = $row2[1];
}
array_push($Q_and_Cs, $questions);
}
}
mysqli_close($dbc);
// Generate the quiz form by looping through the questions array
echo '<form method="post" action="' . $_SERVER['PHP_SELF'] . '">';
echo '<h2>' . $quiz_title . '</h2>';
$question_title = $Q_and_Cs[0]['question'];
echo '<label for="' . $Q_and_Cs[0]['r_id'] . '">' . $Q_and_Cs[0]['question'] . '</label><br />';
foreach ($Q_and_Cs as $Q_and_C) {
// Only start a new question if the question changes
if ($question_title != $Q_and_C['question']) {
$question_title = $Q_and_C['question'];
echo '<br /><label for="' . $Q_and_C['r_id'] . '">' . $Q_and_C['question'] . '</label><br />';
}
// Display the choices
// Choice #1
echo '<input type="radio" id="' . $Q_and_C['r_id'] . '" name="' . $Q_and_C['r_id'] . '" value="' . $Q_and_C[0] . '" />' . $Q_and_C[1] . '<br />';
// Choice#2
echo '<input type="radio" id="' . $Q_and_C['r_id'] . '" name="' . $Q_and_C['r_id'] . '" value="' . $Q_and_C[2] . '" />' . $Q_and_C[3] . '<br />';
// Choice #3
echo '<input type="radio" id="' . $Q_and_C['r_id'] . '" name="' . $Q_and_C['r_id'] . '" value="' . $Q_and_C[4] . '" />' . $Q_and_C[5] . '<br />';
// Choice #4
echo '<input type="radio" id="' . $Q_and_C['r_id'] . '" name="' . $Q_and_C['r_id'] . '" value="' . $Q_and_C[6] . '" />' . $Q_and_C[7] . '<br />';
}
echo '<br /><br />';
echo '<input type="hidden" name="quiz_id" value"'.$quiz_id.'" />';
echo '<input type="submit" value="Grade Me!" name="submit" />';
echo '</form>';
// echo 'Quiz_id: '.$quiz_id.'<br />';
// Insert the page footer
require_once('footer.php');
?>
Here is the code for quizlist.php
// Determine number of quizes based on title in quiz table
$query = "SELECT * FROM quiz";
$data = mysqli_query($dbc, $query);
// Loop through quiz titles and display links for each
while ($row = mysqli_fetch_array($data, MYSQL_ASSOC)) {
echo '' . $row['title'] . '<br />';
}
mysqli_close($dbc);
My problem has to do with the piece of code
$query = "INSERT INTO high_score " .
"VALUES ('0', '" . $_SESSION['user_id'] . "', '" . $quiz_id . "', '" . $correct_As . "', NOW())";
It works when I substitute a number (i.e. 2) in the place of $quiz_id, but in order for the script to work for different quizzes I need to be able to use a different quiz_id for different quizzes.
I'm having trouble taking the variable from quizlist.php using $_GET and then passing it along as a hidden value when the form is submitted. Am I doing something incorrect? Or am I missing something completely obvious? I'd appreciate any help! Thanks...

Answer 1

On the first clue, it seems to me that you're getting your $quiz_id form GET request (and that's correct), but you have a condition
if (isset($_POST['submit'])) {
which is fulfilled only when form is submitted (POST request), not link clicked. So all the code under this condition is not executed when you click the link