WITH numseq as(
SELECT MONTHLY,
NEW_MRR+EXPANSION_MRR-
DOWNGRADE_MRR-CHURN_MRR as num
FROM MRR_DATA
),
cum as (SELECT
MONTHLY as YM,
SUM(num) OVER (ORDER BY MONTHLY) as MRR
FROM numseq
)
SELECT YM,
COALESCE(LAG(MRR) OVER(ORDER BY YM),0)as MRR
FROM cum
ORDER BY YM