<?php
session_start();

//This displays your login form
function index(){

echo "<form action='?act=login' method='post'>"
."Username: <input type='text' name='username' size='30'><br>"
."Password: <input type='password' name='password' size='30'><br>"
."<input type='submit' value='Login'>"
."</form>";

}

//This function will find and checks if your data is correct
function login(){

//Collect your info from login form
$username = $_REQUEST['username'];
$password = $_REQUEST['password'];


//Connecting to database
$connect = mysql_connect("host", "username", "password");
if(!$connect){
die(mysql_error());
}

//Selecting database
$select_db = mysql_select_db("database", $connect);
if(!$select_db){
die(mysql_error());
}

//Find if entered data is correct

$result = mysql_query("SELECT * FROM users WHERE username='$username' AND password='$password'");
$row = mysql_fetch_array($result);
$id = $row['id'];

$select_user = mysql_query("SELECT * FROM users WHERE id='$id'");
$row2 = mysql_fetch_array($select_user);
$user = $row2['username'];

if($username != $user){
die("Username is wrong!");
}


$pass_check = mysql_query("SELECT * FROM users WHERE username='$username' AND id='$id'");
$row3 = mysql_fetch_array($pass_check);
$email = $row3['email'];
$select_pass = mysql_query("SELECT * FROM users WHERE username='$username' AND id='$id' AND email='$email'");
$row4 = mysql_fetch_array($select_pass);
$real_password = $row4['password'];

if($password != $real_password){
die("Your password is wrong!");
}



//Now if everything is correct let's finish his/her/its login

session_register("username", $username);
session_register("password", $password);

echo "Welcome, ".$username." please continue on our <a href=index.php>Index</a>";




}

switch($act){

default;
index();
break;

case "login";
login();
break;

}
?>