Query for remaining balance - sql

Question

Query for remaining balance
I am using SQLITE 3.1.1
The scenario is the ff:
Let us say Total Quantity is 11.
The formula should be:
Total Quantity - Quantity Used = Remaining
It should look like this:
First: 11 - 1 = 10
Second: 10- 6 = 4
Third: 4 - 0 = 4
and so on..
Expected Result:
Also, Remaining value can't be lower than 0.
I currently have this SQL query but it doesn't get the Remaining query result for the next transaction but rather it always starts with Total Quantity.
SELECT
filter_maintenance.maintenance_id,
filter_maintenance.stock_id,
filter_maintenance.quantity_used,
filter_maintenance.date_registered,
filter_maintenance.date_changed,
inventories.stock_name,
SUM(inventories_order.order_quantity) - filter_maintenance.quantity_used AS Remaining
FROM filter_maintenance
INNER JOIN inventories ON filter_maintenance.stock_id = inventories.stock_id
INNER JOIN inventories_order ON filter_maintenance.stock_id = inventories_order.stock_id
GROUP BY filter_maintenance.maintenance_id
This is the output I currently have:
Your help is greatly appreciated. Thank you in advance.

Answer 1

Since you are using sqllite and there are no window functions you need to use a self-join instead. I assume maintenance_id is a primary key in filter_maintenance.
SELECT
filter_maintenance.maintenance_id,
filter_maintenance.stock_id,
filter_maintenance.quantity_used,
filter_maintenance.date_registered,
filter_maintenance.date_changed,
inventories.stock_name,
sum(inventories_order.order_quantity) - filter_maintenance.sum_quantity_used AS Remaining
FROM
(
SELECT fm1.*,
sum(fm2.quantity_used) AS sum_quantity_used
FROM filter_maintenance fm1
INNER JOIN filter_maintenance fm2 ON fm1.stock_id = fm2.stock_id and
fm1.date_registered >= fm2.date_registered
GROUP BY fm1.maintenance_id
) filter_maintenance
INNER JOIN inventories ON filter_maintenance.stock_id = inventories.stock_id
INNER JOIN inventories_order ON filter_maintenance.stock_id = inventories_order.stock_id
GROUP BY filter_maintenance.maintenance_id