i have two selects a & b and i join them like:

select * from 
(
   select n.id_b || ',' || s.id_b ids, n.name, s.surname 
   from names n, 
        surnames s where n.id_a = s.id_a
) a 
left join
(
    select sn.id, sn.second_name
) b on b.id in (a.ids)

in this case join doesn't work :( The problem is in b.id in (a.ids). But why if it looks like 12 in (12,24) and no result :(