WITH
    monthly_mrr AS (
        SELECT
            DATE (MONTHLY, '+1 months') nxt
          , (
                SUM(NEW_MRR) OVER (
                    ORDER BY
                        MONTHLY
                ) + SUM(EXPANSION_MRR) OVER (
                    ORDER BY
                        MONTHLY
                ) - SUM(DOWNGRADE_MRR) OVER (
                    ORDER BY
                        MONTHLY
                ) - SUM(CHURN_MRR) OVER (
                    ORDER BY
                        MONTHLY
                )
            ) AS hoge
        FROM
            MRR_DATA
    )
SELECT
    MONTHLY AS YM
  , CASE
        WHEN hoge IS NULL THEN 0
        ELSE hoge
    END MMR
FROM
    (
        SELECT
            MONTHLY
        FROM
            MRR_DATA
        UNION ALL
        SELECT
            (DATE (MAX(MONTHLY), '+1 months'))
        FROM
            MRR_DATA
    ) mr
    LEFT JOIN monthly_mrr mo ON mo.nxt = mr.MONTHLY
ORDER BY
    MONTHLY;