with 
t_monthry as(
    select * from MRR_DATA
    union all
    select date(max(monthly), '+1 month'),0,0,0,0
    from MRR_DATA
),
t_mrr as (
    select *, 0 as MRR FROM t_monthry WHERE monthly = (select min(monthly) from t_monthry)
    union all
    select x.*,
        pre.MRR + pre.NEW_MRR + pre.EXPANSION_MRR - pre.DOWNGRADE_MRR - pre.CHURN_MRR as MRR
        FROM t_monthry as x, t_mrr as pre
        WHERE pre.monthly = date(x.monthly, '-1 month')
)

select
monthly AS YM,
MRR AS MRR
from t_mrr
order by monthly