<?php
session_start();

if (isset($_POST["username"]) && isset($_POST["password"])) {

	$username = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["username"]);
    $password = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["password"]);
    include "connect_to_mysql.php";
    $sql = mysql_query("SELECT id FROM users WHERE username='$username' AND password='$password' LIMIT 1");
    $existCount = mysql_num_rows($sql);
    if ($existCount == 1)
	     while($row = mysql_fetch_array($sql)){
             $id = $row["id"];{
		 }
		 $_SESSION["id"] = $id;
		 $_SESSION["username"] = $username;
		 $_SESSION["password"] = $password;
		 $_SESSION["name"] = $name;
		 header("location:instructions.php");
         exit();
    } else {
		echo 'That information is incorrect, try again <a href="login.php">Click Here</a>';
		exit();
	}
}

?>