Vaste waarde per maand splitsen naar elke dag en land

U moet de FROM . herstellen clausule, dus je neemt alleen de vaste kosten per maand mee:

FROM sales s CROSS JOIN
     (SELECT LAST_DAY(sales_date) as month_ld, SUM(fix_costs) as fix_costs
      FROM sales
      WHERE country = 'None'
      GROUP BY month_ld
     ) f
     ON f.month_ld = LAST_DAY(s.sales_date)