<?php
    session_start();
    ?>

    <?php

    $DB_SERVER="localhost";
    $DB_USER="root";
    $DB_PASS="new_password";
    $DB_NAME="userlistdb";

    $link=mysqli_connect($DB_SERVER,$DB_USER,$DB_PASS,$DB_NAME);

    if(isset($_SESSION["session_username"])){
    header("Location: intropage.php");
    }
    if(isset($_POST["login"])){
    if(!empty($_POST['username']) && !empty($_POST['password'])) {
    $username=htmlspecialchars($_POST['username']);
    $password=htmlspecialchars($_POST['password']);
    //var_dump($_POST);
    $query=mysqli_query($link,"SELECT * FROM usertbl WHERE username='".$username."' AND password='".$password."'");
    //print_r($query);
    $numrows=mysqli_num_rows($link,$query);
    print_r($numrows);
if($numrows!=0)
 {
while($row=mysqli_fetch_assoc($query))
 {
    $dbusername=$row['username'];
    $dbpassword=$row['password'];
var_dump($row);
 }

/*echo $dbusername;
echo $dbpassword;
echo $username;
echo $password;
*/
  if($username == $dbusername && $password == $dbpassword)
//  if (true)
 {
    $_SESSION['session_username']=$username;
   header("Location: intropage.php");
    }
    } else {
    echo  "Invalid username or password!";
 }
    } else {
    $message = "All fields are required!";
    }
    }
    ?>

<?php include("includes/header.php"); ?>

<div class="container mlogin">
<div id="login">
<h1>Вход</h1>
<form action="" id="loginform" method="post"name="loginform">
<p><label for="user_login">Имя опльзователя<br>
<input class="input" id="username" name="username"size="20"
type="text" value=""></label></p>
<p><label for="user_pass">Пароль<br>
 <input class="input" id="password" name="password"size="20"
  type="password" value=""></label></p>
    <p class="submit"><input class="button" name="login"type= "submit" value="Log In"></p>
    <p class="regtext">Еще не зарегистрированы?<a href= "regg.php">Регистрация</a>!</p>
   </form>
 </div>
  </div>
<?php include("includes/footer.php"); ?>