Want to return 0 in the integer list IF SUM(something) is null

Question

So, I am using Room in Java in Android.

I am returing the list of payment from the database like this

"SELECT IFNULL(SUM(payment), 0) FROM works_db_table WHERE account_year = :year " +
" GROUP BY account_month ORDER BY account_month 

But, it returns nothing if the payment of certain month is 0. For instance, if payment for month 1 is 200, payment for month 2 is 0, and payment for month 3 is 100, it will return [200, 100], not [200, 0, 100).

I have tried with IFNULL, but happens the same.

The answer of @forpas fixed this, but his code has some errors. The code below is slightly modified version of his code-

  SELECT Ifnull(Sum(w.payment), 0)
FROM   (SELECT 1 month
        UNION ALL
        SELECT 2
        UNION ALL
        SELECT 3
        UNION ALL
        SELECT 4
        UNION ALL
        SELECT 5
        UNION ALL
        SELECT 6
        UNION ALL
        SELECT 7
        UNION ALL
        SELECT 8
        UNION ALL
        SELECT 9
        UNION ALL
        SELECT 10
        UNION ALL
        SELECT 11
        UNION ALL
        SELECT 12) m
       LEFT JOIN works_db_table w
              ON w.account_month = m.month
                 AND w.account_year = :year
GROUP  BY m.month 

Answer 1

You need a query that returns all the months 1-12 and then LEFT join it to the table:

SELECT IFNULL(SUM(w.payment), 0) 
FROM (
  SELECT 1 month UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
  SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8
  SELECT 9 UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12
) m LEFT JOIN works_db_table w
ON w.account_month =  m.month AND w.account_year = :year 
GROUP BY m.month