21 - Login validation code in PHP

Database credentials

<?php
  define('DB_SERVER', 'localhost');
  define('DB_USERNAME', 'username');
  define('DB_PASSWORD', 'password');
  define('DB_DATABASE', 'database');
  $db = mysqli_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD,DB_DATABASE);

Lock.php

<?php
  include('config.php');
  session_start();
  $user_check=$_SESSION['login_user'];

  $ses_sql=mysqli_query($db,"select username from admin where username='$user_check' ");
  $row=mysqli_fetch_array($ses_sql,MYSQLI_ASSOC);
  $login_session=$row['username'];
  if(!isset($login_session))
  {
   header("Location: login.php");
  }
?>

Login.php

<?php

include("config.php");
session_start();

  if($_SERVER["REQUEST_METHOD"] == "POST")
  {
   // username and password sent from form 
     $myusername=mysqli_real_escape_string($db,$_POST['username']); 
     $mypassword=mysqli_real_escape_string($db,$_POST['password']); 

     $sql="SELECT id FROM admin WHERE username='$myusername' and passcode='$mypassword'";
     $result=mysqli_query($db,$sql);
     $row=mysqli_fetch_array($result,MYSQLI_ASSOC);
     $active=$row['active'];

     $count=mysqli_num_rows($result);

    // If result matched $myusername and $mypassword, table row must be 1 row
    if($count==1)
    {
     session_register("myusername");
     $_SESSION['login_user']=$myusername;

     header("location: welcome.php");
    }
    else 
    {
    $error="Your Login Name or Password is invalid";
    }
  }
?>

HTML code

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
   <title>Login Page</title>
   <style type="text/css">
     body
     {
      font-family:Arial, Helvetica, sans-serif;
      font-size:14px;
     }
     label
     {
     font-weight:bold;
     width:100px;
     font-size:14px;
     }
     .box
    {
    border:#666666 solid 1px;
    }
   </style>
  </head>
  <body bgcolor="#FFFFFF">
   <div><h3>Tutorial link <a href="">Click Here</a></h3></div>
   <div style="font-weight:bold; margin-bottom:10px">Demo Login Details -> Username : <a href="#">test</a>  Password : <a href="#">test</a></div>
   <div align="center">
    <div style="width:300px; border: solid 1px #333333; " align="left">
     <div style="background-color:#333333; color:#FFFFFF; padding:3px;"><b>Login</b></div>
     <div style="margin:30px">
      <form action="" method="post">
        <label>UserName  :</label><input type="text" name="username" class="box"/><br /><br />
        <label>Password  :</label><input type="password" name="password" class="box" /><br/><br />
        <input type="submit" value=" Submit "/><br />
      </form>
      <div style="font-size:11px; color:#cc0000; margin-top:10px"><?php echo $error; ?></div>
     </div>
    </div>
   </div>
  </body>
</html>

Logout.php

<?php
  session_start();
  if(session_destroy())
  {
   header("Location: login.php");
  }
?>

Welcome.php

<?php

  include('lock.php');

?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
    <title>Welcome </title>
  </head>

  <body>
    <h1>Welcome <?php echo $login_session; ?></h1> 
    <h2><a href="www.wideskills.com">wideskills.com</a></h2>
    <h2><a href="logout.php">Sign Out</a></h2>
  </body>
</html>

 

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