tabekg/config.php

## config.php
<?php
session_start();

$db = new mysqli('localhost', 'root', '', 'youtube'); // базаны тууралаңыз!!!

function getSession($name, $delete = true){
	$data = $_SESSION[$name];
	if ($delete) $_SESSION[$name] = NULL;
	return $data;
}

function checkUser(){
	global $db;
	$query = $db->query('SELECT COUNT(*) AS `c` FROM `users` WHERE `login`="' . $_COOKIE['login'] . '" and `password`="' . $_COOKIE['password'] . '"')->fetch_assoc();
	return $query['c'] > 0;
}

## index.php
<?php
require_once 'config.php';

if (checkUser()){
	$login = $_COOKIE['login'];
} else header('Location: login.php');
?>
<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>Кош келиңиз!</title>
	<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
	<h2>Кош келиңиз, <?=$login?>!</h2>
	<div><a href="logout.php">Чыгуу</a></div>
</body>
</html>

## login.php
<?php
require_once 'config.php';

if (checkUser()) header('Location: index.php');

if ($_SERVER['REQUEST_METHOD'] == 'POST'){
	$login = $_POST['login'];
	$password = $_POST['password'];
	if ($login != '' && $password != ''){
		$query = $db->query('SELECT COUNT(*) AS `c` FROM `users` WHERE `login`="' . $login . '"')->fetch_assoc();
		if ($query['c'] > 0){
			$query = $db->query('SELECT `password` FROM `users` WHERE `login`="' . $login . '"')->fetch_assoc();
			if (password_verify($password, $query['password'])){
				setcookie('login', $login);
				setcookie('password', $query['password']);
				header('Location: index.php');
			} else {
				$_SESSION['error'] = 'Пароль туура эмес!';
			}
		} else {
			$_SESSION['error'] = 'Логин туура эмес!';
		}
	}
}
?>
<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>Кирүү</title>
	<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
	<h2>Кирүү</h2>
	<?php
	if (getSession('error', false) != '') echo '<div class="error">' . getSession('error') . '</div>';
	?>
	<form method="post">
		<div><input type="text" name="login" placeholder="Логин" required></div>
		<div><input type="password" name="password" placeholder="Пароль" required></div>
		<div><input type="submit" value="Кирүү" /></div>
		<div><a href="register.php">Катталуу</a></div>
	</form>
</body>
</html>

## logout.php
<?php
setcookie('login', '');
setcookie('password', '');
header('Location: login.php');

## register.php
<?php
require_once 'config.php';

if (checkUser()) header('Location: index.php');

if ($_SERVER['REQUEST_METHOD'] == 'POST'){
	$login = $_POST['login'];
	$password = $_POST['password'];
	if ($login != '' && $password != ''){
		$query = $db->query('SELECT COUNT(*) AS `c` FROM `users` WHERE `login`="' . $login . '"')->fetch_assoc();
		if ($query['c'] > 0){
			$_SESSION['error'] = 'Мындай логин бош эмес!';
		} else {
			if ($db->query('INSERT INTO `users` SET `login`="' . $login . '", `password`="' . password_hash($password, PASSWORD_DEFAULT) . '"')){
				$_SESSION['success'] = 'Ийгиликтүү катталдыңыз!';
			} else {
				$_SESSION['error'] = 'Белгисиз катачылык!';
			}
		}
	}
}
?>
<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>Катталуу</title>
	<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
	<h2>Катталуу</h2>
	<?php
	if (getSession('error', false) != '') echo '<div class="error">' . getSession('error') . '</div>';
	if (getSession('success', false) != '') echo '<div class="success">' . getSession('success') . '</div>';
	?>
	<form method="post">
		<div><input type="text" name="login" placeholder="Логин" required></div>
		<div><input type="password" name="password" placeholder="Пароль" required></div>
		<div><input type="submit" value="Катталуу" /></div>
		<div><a href="login.php">Кирүү</a></div>
	</form>
</body>
</html>

## style.css
body {
	text-align: center;
}

input {
	padding: 10px;
	margin: 10px;
}

.error {
	background-color: #f00;
	color: #fff;
	padding: 5px;
	font-size: 14px;
}

.success {
	background-color: #0f0;
	color: #fff;
	padding: 5px;
	font-size: 14px;
}
	<?php
	session_start();

	$db = new mysqli('localhost', 'root', '', 'youtube'); // базаны тууралаңыз!!!

	function getSession($name, $delete = true){
	$data = $_SESSION[$name];
	if ($delete) $_SESSION[$name] = NULL;
	return $data;
	}

	function checkUser(){
	global $db;
	$query = $db->query('SELECT COUNT(*) AS `c` FROM `users` WHERE `login`="' . $_COOKIE['login'] . '" and `password`="' . $_COOKIE['password'] . '"')->fetch_assoc();
	return $query['c'] > 0;
	}
	<?php
	require_once 'config.php';

	if (checkUser()){
	$login = $_COOKIE['login'];
	} else header('Location: login.php');
	?>
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<title>Кош келиңиз!</title>
	<link rel="stylesheet" type="text/css" href="style.css">
	</head>
	<body>
	<h2>Кош келиңиз, <?=$login?>!</h2>
	<div><a href="logout.php">Чыгуу</a></div>
	</body>
	</html>
	<?php
	require_once 'config.php';

	if (checkUser()) header('Location: index.php');

	if ($_SERVER['REQUEST_METHOD'] == 'POST'){
	$login = $_POST['login'];
	$password = $_POST['password'];
	if ($login != '' && $password != ''){
	$query = $db->query('SELECT COUNT(*) AS `c` FROM `users` WHERE `login`="' . $login . '"')->fetch_assoc();
	if ($query['c'] > 0){
	$query = $db->query('SELECT `password` FROM `users` WHERE `login`="' . $login . '"')->fetch_assoc();
	if (password_verify($password, $query['password'])){
	setcookie('login', $login);
	setcookie('password', $query['password']);
	header('Location: index.php');
	} else {
	$_SESSION['error'] = 'Пароль туура эмес!';
	}
	} else {
	$_SESSION['error'] = 'Логин туура эмес!';
	}
	}
	}
	?>
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<title>Кирүү</title>
	<link rel="stylesheet" type="text/css" href="style.css">
	</head>
	<body>
	<h2>Кирүү</h2>
	<?php
	if (getSession('error', false) != '') echo '<div class="error">' . getSession('error') . '</div>';
	?>
	<form method="post">
	<div><input type="text" name="login" placeholder="Логин" required></div>
	<div><input type="password" name="password" placeholder="Пароль" required></div>
	<div><input type="submit" value="Кирүү" /></div>
	<div><a href="register.php">Катталуу</a></div>
	</form>
	</body>
	</html>
	<?php
	setcookie('login', '');
	setcookie('password', '');
	header('Location: login.php');
	body {
	text-align: center;
	}

	input {
	padding: 10px;
	margin: 10px;
	}

	.error {
	background-color: #f00;
	color: #fff;
	padding: 5px;
	font-size: 14px;
	}

	.success {
	background-color: #0f0;
	color: #fff;
	padding: 5px;
	font-size: 14px;
	}