Stuff

        $fields = array(
            'timestamp'=>time(),
            'name' => null,
            'address' => null,
            'zipcode' => null,
            'city' => null,
            'ip' => $_SERVER['REMOTE_ADDR']
        );
        $query = 'INSERT INTO orders ('.join(', ', array_keys($fields)).') VALUES (';
        foreach($fields as $value => $field) {
            if(is_null($value)) {
                $fields[$field] = $orderdata[$field];
            }
        }
        $query .= join(',', array_values($fields)) . ")";