خطا در استفاده تابع hash("sha256",$password);

$password = hash("sha256",$password);


require_once("./inc/Configuretion.php");

$query = "SELECT * FROM users WHERE useame = '".$useame."' and password = '".$password."'";
$res = mysql_query($query, $link);
$row = mysql_fetch_array($res);
if (mysql_num_rows($res) == '1')
{
session_start();
$_SESSION['useame'] = $_POST['si_user'];
$_SESSION['password'] = $_POST['si_user'];
HEADER("LOCATION: home.php");
}
else
{
echo "Error User";
}