Getting the sum of several columns from two tables

Question

I want to get the sum of several columns from 2 different tables (these tables share the same structure).

If I only consider one table, I would write this kind of qu

Answer 1

Have you tried using a union?

SELECT MONTH_REF, SUM(amount1), SUM(amount2)
FROM (
  SELECT MONTH_REF, SUM(amount1) AS amount1, SUM(amount2) as amount2
      FROM T_FOO
      WHERE seller = XXX
      GROUP BY MONTH_REF
  UNION ALL SELECT MONTH_REF, SUM(amount1), SUM(amount2)
      FROM T_BAR
      WHERE seller = XXX
      GROUP BY MONTH_REF
  ) tmp
GROUP BY MONTH_REF