Create a ROLLING sum over a period of time in mysql

Question

I have a table with columns date and time_spent. I want to find for each date D the sum of the values of \'time_spent\' for the period of time : (D

Answer 1

Here you go:

select
t.*,
@total:=@total + t.time_spent - coalesce(t2.time_spent, 0) as your_total_over_last_7_days
from
rolling_total t
left join rolling_total t2 on t.date = t2.date + interval 8 day
, (select @total:=0) v
order by t.`date` 

• see it working live in an sqlfiddle.