Make a monthly report which includes previous month results
my company rent containers to customers. Each month we have to do a balance of containers (returned or rented) for each customer. I have a customer table and another table for containers.
I would like to display a monthly report which include the previous month balance at the top of the layout.
Example for the month of july:
balance from june: returned 5 containers, rented 4 containers, so balance is 4-5 = -1.
01/07/14, 1 returned, 0 rented
02/07/14, 0 returned, 0 rented
31/07/14, 0 returned, 4 rented
balance is 4-1 = 3
do the total balance at the bottom: -1 (june) + 3 (july) = 2
The difficulty is to include the balance of the previous month in the calculation of the current month.
I hope somebody can help,