With cte as (
select  t.city,   t.reportdate, t.type ,min(t.cost), max(t.cost)
FROM
(
select t1.city, t1.type, t1.cost, t1.reportdate
from city_from_base1 t1
union ALL
select t2.city, t2.type, t2.cost, t2.reportdate
from city_from_base2 t2
) t
group by t.city, t.type,  t.reportdate
)
Select * from cte t1 left join cte t2 on t1.city=t2.city
and cast(t1.reportdate as integer) > cast(t2.reportdate as integer)

and cast(t1.reportdate as integer) > cast(t2.reportdate as integer)

With cte as (
select  t.city,   t.reportdate, t.type ,min(t.cost) as min, max(t.cost) as max, row_number() over(partition by t.city) num
FROM
(
select t1.city, t1.type, t1.cost, t1.reportdate
from city_from_base1 t1
union ALL
select t2.city, t2.type, t2.cost, t2.reportdate
from city_from_base2 t2
) t
group by t.city, t.type,  t.reportdate
)
Select *
from cte t1 left join cte t2 on t1.num-1=t2.num and t1.city=t2.city
order by city