WITH T1 AS(
    SELECT
        MONTHLY AS YM
    FROM
        MRR_DATA
),
T2 AS(
    SELECT
        YM,
        MONTHLY,
        NEW_MRR,
        EXPANSION_MRR,
        DOWNGRADE_MRR,
        CHURN_MRR
    FROM
        T1
        CROSS JOIN
            MRR_DATA
)
SELECT
    YM,
    SUM(
        CASE
            WHEN MONTHLY < YM THEN NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR
            ELSE 0
        END
    ) AS MRR
    FROM
        T2
    GROUP BY
        YM