create or alter procedure TEST(ID integer)
returns (VAL varchar(100))
as
begin
  VAL = ID; suspend;
end

select
  (select VAL from TEST(min(r.RDB$RELATION_ID))),
  r.RDB$SYSTEM_FLAG,
  max(r.RDB$RELATION_ID)
from RDB$RELATIONS r
group by 1,2
order by 1