login.php

<?php
session_start();
$arrayerror='';
if (isset($_POST['submit'])) {
if (empty($_POST['username']) || empty($_POST['password'])) {
$arrayerror = "your username or password is empty";
}
else
{
$username=$_POST['username'];
$password=$_POST['password'];
include("configs/connect.php");

$query = mysql_query("select * from st_users where user_password='$password' AND user_name ='$username'");
$rows = mysql_num_rows($query);
if ($rows == 1) {
$_SESSION['login_user']=$username;

header("location: profile.php");
} else {
$arrayerror = "your username or password is invalid ";
}
mysql_close($connection);
}
}
?>
<?php

if(isset($_SESSION['login_user'])){
header("location: profile.php");
}
?>
<!DOCTYPE html>
<html>
<head>
<link href="style.css" rel="stylesheet" type="text/css">
</head>
<body>
<div id="main">
<h1>WELCOM</h1>
<div id="login">
<form action="" method="post">
<label>UserName :</label></br>
<input id="name" name="username" type="text"></br>
<label>Password :</label></br>
<input id="password" name="password" type="password"></br>
<input name="submit" type="submit" value=" Login ">
<span><?php echo $arrayerror; ?></span>
</form>
</div>
</div>
</body>
</html>