Zkuste:
SELECT id
FROM (
SELECT 2 as id
union
SELECT 3
union
SELECT 4
union
SELECT 5
union
SELECT 6
) q
WHERE q.id NOT IN ( SELECT id FROM users )
Zkuste:
SELECT id
FROM (
SELECT 2 as id
union
SELECT 3
union
SELECT 4
union
SELECT 5
union
SELECT 6
) q
WHERE q.id NOT IN ( SELECT id FROM users )