auth.php

<?php

$db_conn = NULL;
$db_username = 'lahtp';
$db_password = 'virtualhostx';
$db_servername = 'localhost';
$db_name = 'lahtp_3_web';

function get_db_connection() {
	global $db_conn;
	global $db_servername;
	global $db_username;
	global $db_password;
	global $db_name;

	if($db_conn != NULL){ //check if an existing connection is open
		return $db_conn; //return the existing connection
	} else { //make a new connection
		$db_conn = mysqli_connect($db_servername, $db_username, $db_password, $db_name);
		if(!$db_conn){
			die("Connection failed: ".mysqli_connect_error());
		} else {
			return $db_conn;
		}
	}
}

function do_login($username, $password){
	$query = "SELECT * FROM lahtp_3_web.auth WHERE username='$username' AND password='$password';";
	$connection = get_db_connection();
	$result = mysqli_query($connection, $query);
	return mysqli_num_rows($result);
}