MySQL cartesian product between two SELECT statements

Question

I want to perform a cartesian product between two SELECT statements as

SELECT 1, 2     INNER JOIN     SELECT 3, 4 ;

I expect the result to

Answer 1

select v1, v2
from
  (select 1 as v1 union
   select 2) t1,
  (select 3 as v2 union
   select 4) t2

or even simpler:

select *
from
  (select 1 union
   select 2) t1,
  (select 3 union
   select 4) t2