WITH MRRTable as
(
    SELECT
    *
    FROM
    MRR_DATA
    LEFT JOIN
    (
        SELECT 
        date(datetime(MONTHLY,'+1 months')) AS MONTHLY,
        NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR AS 前月計算結果
        FROM MRR_DATA
        GROUP BY MONTHLY
    ) a ON a.MONTHLY = MRR_DATA.MONTHLY
),
MRRTable2 as(
    SELECT 
    MRRTable.MONTHLY AS 今月,
    MRRTable.前月計算結果,
    (NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR) AS 今月計算結果
FROM
MRRTable 
GROUP BY 今月
),
MRRTable3 as(
    SELECT
    MRRTable2.今月 AS YM,
    (case 
    when MRRTable2.前月計算結果 IS NULL THEN 0
    else SUM(MRRTable2.前月計算結果) OVER(ORDER BY MRRTable2.今月)
    END) AS MRR
    FROM
    MRRTable2
)

SELECT
*
FROM
MRRTable3