SELECT id
FROM
(
    SELECT 1 AS id
    UNION ALL
    SELECT NULL
    UNION ALL
    SELECT NULL
) js1
ALL FULL OUTER JOIN 
(
    SELECT 1 AS id
    UNION ALL
    SELECT NULL
    UNION ALL
    SELECT NULL
) js2 USING (id)
ORDER BY id;

SELECT '---';

SELECT *
FROM
(
    SELECT NULL AS x
) js1
INNER JOIN 
(
    SELECT NULL AS x
) js2 USING (x);

SELECT '---';

SELECT *
FROM
(
    SELECT NULL AS x
) js1
FULL OUTER JOIN 
(
    SELECT NULL AS x
) js2 USING (x);