Form:
				  <div class="modal fade" id="login-modal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true" style="display: none;">
    	  <div class="modal-dialog">
				<div class="loginmodal-container">
 <h1>Login</h1><br>
  <?php isset($error_msg){ echo $error_msg; } ?>
 <form action="" method="post" name="login">
					<input type="text" name="username" placeholder="Username" required>
					<input type="password" name="password" placeholder="Password" required>
					<input type="submit" name="submit" class="login loginmodal-submit" value="Login">
				  </form>
				</div>
			</div>
		  </div>

PHP
<?php
	require('db1.php');
	session_start();
    if (isset($_POST['username'])){

		$username = stripslashes($_REQUEST['username']);
		$username = mysqli_real_escape_string($con,$username);
		$password = stripslashes($_REQUEST['password']);
		$password = mysqli_real_escape_string($con,$password);

        $query = "SELECT * FROM `users` WHERE username='$username' and password='".md5(	$password)."'";
		$result = mysqli_query($con,$query) or die(mysqli_error());
		$rows = mysqli_num_rows($result);
        if($rows==1){
        $_SESSION['username'] = $username;
        header("Location: view.php");
        }else{
            $error_msg = "<div class='login-modal'>Username or password is incorrect</div>";
            echo "<script> $(document).ready(function(){ $('#login-modal').modal('show'); }); </script>";
            }
    }else{
?>