raw_data as (

select '2021-10-02' as day_date, 5 as borrow, null as repay

union select '2021-10-05' as day_date, null as borrow, -3 as repay

union select '2021-10-06' as day_date, null as borrow, -1 as repay

),

dates as (

-- first argument is unit of time to add, second is amount to increment, third is starting date

dateadd(day, '+' || row_number() over (order by null), '2021-10-01'::date - 1) as day_date

from table (generator(rowcount => 7))

select

d.day_date,

nvl(r.borrow,0) as borrowed_amount,

nvl(r.repay,0) as repaid_amount,

sum(borrowed_amount + repaid_amount) over (order by d.day_date) as net_borrow

from dates d

left join raw_data r on d.day_date = r.day_date