<?php

$username = $_POST['username'];
$password = $_POST['password'];

if ($username&&$password)
{

$connect = mysql_connect("databasehost", "databaseusername", "databasepassword") or die("Couldnt connect!");
mysql_select_db("databasename") or die("Couldn't find db");

$query = mysql_query("SELECT * FROM users WHERE username='$username'");

$numrows = mysql_num_rows($query);

if ($numrows!=0)
{

while ($row = mysql_fetch_assoc($query));
{
  $dbusername = $row['username'];
  $dbpassword = $row['password'];
}
// check to see if they match
if ($username==$dbusername&&$password==$dbpassword)
{
  echo "You're in!";
}
else
    echo "Incorrect password!";
}
else
    die("That user doesn't exsist!");


}
else
    die("Please enter a username and a password!");


?>