Oracle 18c

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create table positif ( trx, nett )
as 
select 3, 2147600 from dual union all
select 3, 2068300 from dual union all
select 4, 50000   from dual union all
select 5, 100000  from dual ;
4 rows affected

create table negatif ( trx, nett )
as
select 3, -1073800 from dual union all
select 3, -1073800 from dual union all
select 3, -2068300 from dual union all
select 4, -20000   from dual union all
select 5, -100000  from dual ;
5 rows affected

select P.trx, P.sum_ totalpos, N.sum_ totalneg
from 
  ( select trx, sum( nett ) sum_ from positif group by trx ) P
  join
  ( select trx, sum( nett ) sum_ from negatif group by trx ) N
  on P.trx = N.trx 
order by 1
;


TRX
TOTALPOS
TOTALNEG


3
4215900
-4215900

4
50000
-20000

5
100000
-100000