[PHP/MySQL] Access denied for user 'ODBC'

<?PHP
session_start();

$host = "localhost";
$user = "odbc";
$pass = "HIDDEN";

$connexion = mysql_connect($host,$user,$pass);

$db = mysql_select_db("membres");


$_SESSION['ip'] = $_SERVER["REMOTE_ADDR"];

$_SESSION['username'] = $_POST['username'];
$_SESSION['md5complet'] = $_POST['md5complet'];
$_SESSION['graindesel'] = $_POST['graindesel_md5'];


$query = "INSERT INTO infos_membres (username,md5,graindesel) VALUES ($username,$md5complet,$graindesel)";

$result = mysql_query($query) or die(mysql_error());


mysql_close();
?>

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ',)' at line 1