Login.php
<?php
require_once('connect.php');
include('includes/head.php');
 ?>

 <form action="<?php $_SERVER['PHP_SELF'] ?>" method="post" >
 <div class="container">
 <fieldset>
 <h2>Login</h2>
 <div class="row">
 <label class="fixedwidth">Username:</label>
 <input type="text" name="username" required />
 </div>
 <div class="row">
 <label class="fixedwidth">Password:</label>
 <input type="password" name="password" />
 </div>
 <div class="row">
 <input type="submit" name="submit" value="LogIn" />
 </div>
 </fieldset>
 </div>
 </form>

 <?php

 if(isset($_POST['submit']))  {
 require_once('connect.php');
 $username = mysqli_real_escape_string($connection, $_POST['username']);
 $password = mysqli_real_escape_string($connection, $_POST['password']);

 if(!empty($username) && !empty($password))  {




    $query = "SELECT * FROM user where username='$username' and
    password='$password'";
    $result = mysqli_query($connection, $query);
    $row=mysqli_fetch_array($result);
    mysqli_close($connection);
    if(mysqli_num_rows($result) ==1)  {


   $fullname=array(firstname=>$row['firstname'],lastname=>$row['lastname']);
    session_start();

    $_SESSION['user'] = $fullname;

    header('Location: welcome.php');

    }
    else    {
        echo "<p>Could not find you in the database.</p>";
    }
    }
    else    {
    echo "<p>Either the username or password are invalid. Please try
    again</p>";
    }


     }
     ?>





Logout.php
<?php
session_start();

unset($_SESSION['user']);
// remove all session variables


session_destroy();
// destroy the session

header('Location: welcome.php');

?>




welcome.php
<?php
include('includes/head.php');
include('includes/nav2.php');
session_start();

echo 'Welcome '. $_SESSION['user'];
echo '<br><br>';
?>