with T1 as (
select MONTHLY,
       DATE(MONTHLY, '+1 month') MP1,
       max(NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR) as PV
from MRR_DATA
group by MONTHLY
order by 1),
   MO_T as (
       select distinct MONTHLY from MRR_DATA union select distinct DATE(MONTHLY, '+1 month') as MONTHLY from MRR_DATA
   )
select MO_T.MONTHLY as YM, sum(coalesce(SUB.PV,0)) as MRR from MO_T left outer join T1 as SUB on MO_T.MONTHLY>SUB.MONTHLY
group by MO_T.MONTHLY
ORDER BY MO_T.MONTHLY
;