SELECT A.MONTHLY AS MONTHLY
      ,CASE
           WHEN IFNULL((SELECT COUNT(Y.MONTHLY) FROM MRR_DATA Y WHERE DATE(Y.MONTHLY, '+1 months') = DATE(A.MONTHLY)), 0) = 0 THEN 0
           ELSE (SELECT SUM(X.NEW_MRR) + SUM(X.EXPANSION_MRR) - SUM(X.DOWNGRADE_MRR) - SUM(X.CHURN_MRR)
                 FROM MRR_DATA X
                 WHERE X.MONTHLY < A.MONTHLY)
       END AS MRR
FROM MRR_DATA A
ORDER BY A.MONTHLY