WITH monthly_data AS (
    SELECT 
        MD.MONTHLY,
        COALESCE(LAG_MD.NEW_MRR, 0) AS PREV_NEW_MRR,
        COALESCE(LAG_MD.EXPANSION_MRR, 0) AS PREV_EXPANSION_MRR,
        COALESCE(LAG_MD.DOWNGRADE_MRR, 0) AS PREV_DOWNGRADE_MRR,
        COALESCE(LAG_MD.CHURN_MRR, 0) AS PREV_CHURN_MRR,
        COALESCE(LAG_MD.MRR, 0) AS PREV_MRR
    FROM 
        MRR_DATA MD
    LEFT JOIN 
        MRR_DATA LAG_MD
    ON 
        strftime('%Y-%m', datetime(MD.MONTHLY, '-1 month')) = LAG_MD.MONTHLY
)
SELECT 
    MONTHLY AS YM, 
    PREV_MRR + PREV_NEW_MRR + PREV_EXPANSION_MRR - PREV_DOWNGRADE_MRR - PREV_CHURN_MRR AS MRR
FROM 
    monthly_data
ORDER BY 
    YM;