How do I join these two selects, what am I doing wrong? - sql

Question

Ok the task at hand is
Obtain the sum of the prizes that have been distributed the exhibitions, until August 31, 2017, for collections and photos. We assume that the awards have never been deserted.
And my code is more or less this
select t1.exhibitions, t2.exhibitions
from (
select exhibitions.premioc
from exhibitions
where EXISTS (select exhibitions.priceC
from exhibitions
join presentCo on exhibitions.id_e = presentCo.id_e
where presentaco.premiada > 0
group by exhibitions.priceC
)
) as t1
left outer join (select exhibitions
from exhibitions
where EXISTS (select exhibitions.priceF
from exhibitions
join presentFo on exhibitions.id_e = presentFo.id_e
where presentafo.preiceC > 0
group by exhibitions.priceF
)
) as "t2"
on t1.exhibitions= t2.exhibitions;
My problem is that I kinda don't know enough of the syntax in SQL and fumbling last minute before delivery (school assignment). I have tried to search and get things to work but I have no idea what I am doing wrong with this part. Any pointer would be awesome. Thank you very much for anything
Edit: being way to late in the night when I posted it I never mentioned the real problem, I get SQL Error: ORA-00933: SQL command not properly ended and don't really get why.

Answer 1

for:
sum of all prizes
distributed at exhibitions, until August 31, 2017
a query would look something like this:
select sum(prize_money)
from exhibitions
where exhibition_date < '2017-09-01'
I suspect the answer is much simpler then you first thought
----
Your existing query has several problems that I an see:
select t1.exhibitions -- this column is not returned by subquery t1
, t2.exhibitions
from (
select exhibitions.premioc -- only this column is returned by subquery t1
from exhibitions
where EXISTS -- when using EXISTS you need a "correlation" inside the where clause of the subquery
(select exhibitions.priceC
from exhibitions
join presentCo on exhibitions.id_e = presentCo.id_e
where presentaco.premiada > 0 -- there is NO "correlation" here
group by exhibitions.priceC
)
) as t1
left outer join (select exhibitions
from exhibitions
where EXISTS ( -- when using EXISTS you need a "correlation" inside the where clause of the subquery
select exhibitions.priceF
from exhibitions
join presentFo on exhibitions.id_e = presentFo.id_e
where presentafo.preiceC > 0 -- there is NO "correlation" here
group by exhibitions.priceF
)
) as "t2"
on t1.exhibitions= t2.exhibitions;
----
I suggest you need to start new, maybe with this as a starting point?
SELECT
exhibitions.id_e
, COALESCE(c.prize_c, 0) prize_c
, COALESCE(f.prize_f, 0) prize_f
FROM exhibitions
LEFT JOIN (
SELECT
presentCo.id_e
, SUM(prize) prize_c
FROM presentCo
GROUP BY
presentCo.id_e
) AS c ON exhibitions.id_e = c.id_e
LEFT JOIN (
SELECT
presentFo.id_e
, SUM(proze) price_f
FROM presentFo
GROUP BY
presentFo.id_e
) AS f ON exhibitions.id_e = presentFo.id_e
But I shall not attempt further suggestions unless I see "sample data" (for each table) and, the "expected result"