Código PHP:
<?php
include('inc/conexion.php');
$username = $_POST['username'];
$password = $_POST['password'];
$result = mysql_query("SELECT * FROM users WHERE username='".$username."'");
while ($cla = mysql_fetch_assoc($result))
{
if($cla['password'] == sha1(md5($password)))
{
echo 'Hola';
}
else
{
echo 'chau';
}
}
?>