coba saja

<?php
date_default_timezone_set('Asia/Jakarta');
$localhostdb = 'localhost';
$usernamedb = 'root';
$passworddb = '';
$dbname = 'myown';
$con =mysql_connect($localhostdb,$usernamedb,$passworddb)or die("cannot connect");
$r=mysql_select_db($databasedb)or die("cannot select DB");
?>
<!--function.php-->
<?php
require_once('database.php');
function doLogin($_POST)
{
$username = $_POST['inputUsername'];
$password = $_POST['inputPassword'];
$encrypt = md5($password);

$rs = mysql_query("select * from m_user where username = '$username' and password = '$encrypt'") or die(mysql_error());
$user = mysql_fetch_array($rs);
}