I'm building a basic website that will offer a quiz dynamically generated from a MySQL database. Based on my current database schema, I'm having trouble understanding how I will generate the 'choices' to different questions in a Quiz Web App.
Here is the database schema:
CREATE TABLE user (
user_id INT UNSIGNED PRIMARY KEY,
username VARCHAR(32) NOT NULL UNIQUE,
password VARCHAR(128) NOT NULL,
...
) Engine=InnoDB;
CREATE TABLE quiz (
quiz_id INT UNSIGNED PRIMARY KEY,
title VARCHAR(64)
) Engine=InnoDB;
CREATE TABLE question (
question_id INT UNSIGNED PRIMARY KEY,
quiz_id INT UNSIGNED NOT NULL,
question VARCHAR(1024),
FOREIGN KEY (quiz_id) REFERENCES quiz (quiz_id)
) Engine=InnoDB;
CREATE TABLE question_choices (
choice_id INT UNSIGNED PRIMARY KEY,
question_id INT UNSIGNED NOT NULL,
is_correct_choice TINYINT(1),
choice VARCHAR(512),
FOREIGN KEY (question_id) REFERENCES question (question_id)
) Engine=InnoDB;
CREATE TABLE quiz_response (
response_id INT UNSIGNED PRIMARY KEY,
user_id INT UNSIGNED NOT NULL,
question_id INT UNSIGNED NOT NULL,
response INT UNSIGNED NOT NULL,
is_correct TINYINT(1),
answer_time FLOAT,
UNIQUE KEY (user_id, question_id)
FOREIGN KEY (user_id) REFERENCES user (user_id),
FOREIGN KEY (question_id) REFERENCES question (question_id),
FOREIGN KEY (response) REFERENCES question_choices (choice_id),
) Engine=InnoDB;
Here is the code I have produced so far in my quiz.php script:
// If this user has never taken this quiz, insert empty responses into the quiz_response table
$query = "SELECT * FROM quiz_response WHERE user_id = '" . $_SESSION['user_id'] . "'";
$data = mysqli_query($dbc, $query);
if (mysqli_num_rows($data) == 0) {
//First grab the list of questions to create empty responses
//Grab all questions from question table
//Rework code in the future to accommodate multiple quizes
$query = "SELECT question_id from question";
$data = mysqli_query($data, $query);
$questionIDs = array();
while ($row = mysqli_fetch_array($data)) {
array_push($questionIDs, $row['question_id']);
}
// Insert empty response rows into the response table, one row per question
foreach ($questionIDs as $question_id) {
$query = "INSERT INTO quiz_response (user_id, question_id) VALUES ('" . $_SESSION['user_id']. "', '$question_id')";
mysqli_query($dbc, $query);
}
}
// If the quiz form has been submitted, write the form responses to the database
if (isset($_POST['submit'])) {
// Write the quiz response rows to the response table
foreach ($_POST as $response_id => $response) {
$query = "UPDATE quiz_response SET response = '$response' WHERE response_id = '$response_id'";
mysqli_query($dbc, $query);
}
echo '<p>Your responses have been saved.</p>
}
// Grab the response data from the database to generate the form
$query = "SELECT qr.response_id, qr.question_id, qr.response, q.question, quiz.quiz " .
"FROM quiz_response AS qr " .
"INNER JOIN question AS q USING (question_id) " .
"INNER JOIN quiz USING (quiz_id) " .
"WHERE qr.user_id = '" . $_SESSION['user_id'] . "'";
$data = mysqli_query($dbc, $query);
$responses = array();
while ($row = mysqli_fetch_array($data)) {
// 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);
$choices = array();
while ($row2 = mysqli_fetch_array($data2)) {
array_push($choices, $row2);
}
// Rename choices
// Eventually push choices into $responses array
// array_push($responses, $row);
}
mysqli_close($dbc);
// Generate the quiz form by looping through the response array
echo '<form method="post" action="' . $_SERVER['PHP_SELF'] . '">';
echo '<h2>' . $page_title . '</h2>';
$question_title = $responses[0]['question'];
echo '<label for="' . $responses[0][response_id'] . '">' . $responses[0]['question'] . '</label><br />';
foreach ($responses as $response) {
// Only start a new question if the question changes
if ($question_title != $response['question']) {
$question_title = $response['question'];
echo '<br /><label for="' . $response['response_id'] . '">' . $response['question'] . '</label><br />';
}
// Display the choices
// Choice 1
// Choice 2
// Choice 3
// Choice 4
}
echo '<br /><br />';
echo '<input type="submit" value="Grade Me!" name="submit" />';
echo '</form>';
I'm having trouble pulling the choice options out of the question_choice table and using them to populate the form. Can I put the choice_id and choice columns into the $responses array and access them in the generating form section without renaming them? At this point I feel I need to rename. Any help would be greatly appreciated!
$choices.<br/>to lay out your form, use CSS (or a list element, which would be semantic). Is the missing single quote representative of your production code?