How to determine natural numbers

CREATE TABLE Nothing (God XML );

- zero
SELECT count (*) AS X FROM
Nothing;

- one
SELECT count (*) AS X FROM
( SELECT count (*) AS X FROM Nothing) X;
')
- two
SELECT count (*) AS X FROM
( SELECT count (*) AS X FROM Nothing
UNION
SELECT count (*) AS X FROM ( SELECT count (*) AS X FROM Nothing) X) X;

- and so on ...