mysql — msqli_error () помогите пожалуйста Я новичок в переполнении стека

Когда я пытаюсь запустить следующий код, выдает мне эту ошибку:

Сообщение об ошибке

Warning: mysqli_error() expects exactly 1 parameter, 0 given in
FUNCTIONS.PHP on line 5
Database query failed

Код

<?php
//This File is the place to store all basic functions
function confirm_query($result_set){
if (!$result_set) {
die("Database query failed" . mysqli_error());
}
}
function get_all_subjects() {
global $connection;
$query = "SELECT *
FROM subjects
ORDER BY position ASC";
$subject_set = mysqli_query($connection, $query);
confirm_query($subject_set);
return $subject_set;
}
function get_pages_for_subjects($subject_id) {
global $connection;
$query = "SELECT *
FROM tblPages
WHERE subject_id = {$subject_id}
ORDER BY position ASC";

$page_set = mysqli_query($connection, $query);
confirm_query($page_set);
return $page_set;
}
function get_subject_by_id($subject_id){
global $connection;
$query = "SELECT * ";
$query .= "FROM subjects ";
$query .= "WHERE id=" . $subject_id ." ";
$query .= "LIMIT 1";
$result_set = mysqli_query($connection, $query);
confirm_query($result_set);// REMEMBER:
// if no rows are returned, fetch_array will return false
if ($subject = mysqli_fetch_array($result_set)){
return $subject;
} else {
return NULL;
}
}
?>