WITH TBL AS(
    SELECT
        (SELECT MIN(MONTHLY) FROM MRR_DATA) AS YM,
        0 AS MRR
    UNION ALL
    SELECT
        DATE(YM,'1 month'),
        MRR+NEW_MRR+EXPANSION_MRR-DOWNGRADE_MRR-CHURN_MRR
    FROM
        TBL
        INNER JOIN MRR_DATA
            ON MRR_DATA.MONTHLY=TBL.YM
    WHERE
        YM < DATE((SELECT MAX(MONTHLY) FROM MRR_DATA),'1 month')
    )

SELECT * FROM TBL ORDER BY YM;