select 
    MONTHLY,
    coalesce(LAG(NEW_MRR) OVER(order by MONTHLY),0)
      + coalesce(LAG(EXPANSION_MRR) OVER(order by MONTHLY),0)
      - coalesce(LAG(DOWNGRADE_MRR) OVER(order by MONTHLY),0)
      - coalesce(LAG(CHURN_MRR) OVER(order by MONTHLY),0) as MRR
from MRR_DATA
order by 1