I have a task that I want to Count the re order count like (quantity available - min stock count) then i hope to if min stock count is lower than Quantity availble, notify to purticular supplier, min stock count is we can include, no issue, How can we gain the Quantity availabe in already exist as (on hand count in odoo purchase and Inventory platform) it isn't in database, How can i add this? Mainly I need this calculation guidance? How to interact with db?