Submitted by: @dyemanov

Is related to QA373

Test case:

select rdb$relation_id as c from rdb$relations
group by 1
-- correct result

select * from (
select rdb$relation_id as c from rdb$relations
) group by 1
-- also correct

select coalesce(rdb$relation_id, 0) as c from rdb$relations
group by 1
-- ERROR: no zero ID is reported, the last ID is reported twice

select * from (
select coalesce(rdb$relation_id, 0) as c from rdb$relations
) group by 1
-- ERROR: single NULL is returned

I doubt the third and fourth samples represent the same bug, as if I replace COALESCE with ROUND, the third one succeeds while the fourth one still returns NULL.

Commits: 720a49c dcfdeca

====== Test Details ======

Test probably should be re-implemented: it hopes that in the future FB-versions there will be NO system tables (which currently not exists) with rdb$relations.rdb$relation_id < 30.