sql - Complex Postgres query -


i have db schema following - 

(country table) | country | country code|  -------------------------     abc              bcd         b

(organization table)

|organization | country code | organization code

org 1                           o1 org 2            b                o2 org 3                           o3

(transaction table)

| organization | export(in $) | import(in $)|

 o1             x1                y1  o2             x2                y2  o3             x3                y3

i want result set - 

| corridor | total export | total import | ------------------------------------------   abc-bcd      x1+x2+x3       y1+y2+y3

corridor column should combination of countries in country table.

how can form query implement logic? thanks

all need run aggregate query:

select sum(t.export) totalexport, sum(t.import) totalimport country c inner join organization o on c.country_code = o.country_code inner join transaction t on o.organization_code = t.organization_code

now, ask: corridor column? answer is: use string_agg function:

select string_agg(distinct c.country, '-' order c.country) corridor, sum(t.export) totalexport, sum(t.import) totalimport country c inner join organization o on c.country_code = o.country_code inner join transaction t on o.organization_code = t.organization_code

-

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