Oracle SQL order by in subquery problems!

Question

I am trying to run a subquery in Oracle SQL and it will not let me order the subquery columns. Ordering the subquery is important as Oracle seems to choose at will which of

Answer 1

I've experienced this myself and you have to use ROW_NUMBER(), and an extra level of subquery, instead of rownum...

Just showing the new subquery, something like...

(
  SELECT
    last_updated
  FROM
  (
    select
      last_updated,
      ROW_NUMBER() OVER (ORDER BY last_updated ASC) row_id
    from
      mwcrm.process_state_transition subpst
    where
      subpst.last_updated > pst.last_updated
      and subpst.process_state = ps.id
  )
    as ordered_results
  WHERE
    row_id = 1
)
  as next_response

An alternative would be to use MIN instead...

(
  select
    MIN(last_updated)
  from
    mwcrm.process_state_transition subpst
  where
    subpst.last_updated > pst.last_updated
    and subpst.process_state = ps.id
)
  as next_response