$sql = "INSERT INTO fetss.ocs_extended(ocsID, internalNOTE)
            VALUES('" .(int)$_POST['id'] ."', '". $db- >quote($_POST['note_desc']) ."')
            ON DUPLICATE KEY UPDATE internalNOTE = VALUES('". $db->quote($_POST['note_desc']) ."')";

$sql = "INSERT INTO database.tablename(ID, Description)
VALUES(ID, Description) on Duplicate Key Update Description = VALUES(Description)"

$sql = sprintf("INSERT INTO fetss.ocs_extended(`ocsID`, `internalNOTE`)
                VALUES(%d, '%s')
                ON DUPLICATE KEY UPDATE
                `internalNOTE` = VALUES(`internalNOTE`)",
                (int)$_POST['id'],
                $db->quote($_POST['note_desc']));

INSERT INTO foo (id, desc) VALUES(1, 'testing')
ON DUPLICATE KEY UPDATE
desc = 'some other string that is not testing';