generate empty rows even if empty between 2 dates

Question

I have this simple query that fetches all completed orders between 2 dates(about 6 months at a time):

select IFNULL(sum(o.amount), 0) as amount, o.completed_         


        

Answer 1

This query is complicated due to a number of factors.

The easiest solution might be to add a 0 amount on the first of each month.