function delete_quiz($quiz_id)
{
//delete questions
$query = he_database::placeholder("SELECT `id` FROM `se_he_quiz_question` \r\n WHERE `quiz_id`=?", $quiz_id);
$question_ids = he_database::fetch_column($query);
he_quiz::delete_questions($question_ids);
//delete results
$query = he_database::placeholder("SELECT `id` FROM `se_he_quiz_result`\r\n WHERE `quiz_id`=?", $quiz_id);
$result_ids = he_database::fetch_column($query);
he_quiz::delete_results($result_ids);
//delete plays
$query = he_database::placeholder("DELETE FROM `se_he_quiz_play`\r\n WHERE `quiz_id`=?", $quiz_id);
he_database::query($query);
//get quiz photo
$query = he_database::placeholder("SELECT `photo` FROM `se_he_quiz`\r\n WHERE `quiz_id`=?", $quiz_id);
$photo = he_database::fetch_field($query);
if ($photo) {
//delete photo
@unlink(he_quiz::photo_dir() . $photo);
}
//delete comments
$query = he_database::placeholder("DELETE FROM `se_he_quizcomments`\r\n WHERE `he_quizcomment_quiz_id`=?", $quiz_id);
//delete quiz
$query = he_database::placeholder("DELETE FROM `se_he_quiz` WHERE `quiz_id`=?", $quiz_id);
he_database::query($query);
}