add 1 month to date

[bytM3]

ok guys, another learning experience....I want to add 1 month to a duedate and update. How to include:

(SET duedate = DATE_ADD(duedate, INTERVAL 1 month )

into this:

$sql = "UPDATE payfile SET
amtpaid=?, duedate=?, prevbal=?, latechg=?, secdep=?, damage=?, courtcost=?, nsf=?, hudpay=?, datepaid=?, paidsum=?
WHERE id=?";
$stmt = $conn->prepare($sql);
$stmt->bind_param("dsdddddddsdi", $amtpaid, $duedate, $prevbal, $latechg, $secdep, $damage, $courtcost,
$nsf, $hudpay, $datepaid, $paidsum, $id);
$stmt->execute();