How can I change "available stocks" number on inventory table by the selection of product code

[liqma229]

Hi,

Im making an inventory management app that has a function to release products to an another branch (internal use). The basics work perfectly fine, complete the release form and such, but I would like to make it less confusing by adding decrease available stocks number to 0 once the products had been selected on the form to avoid duplicates item. Each item is uniquely assigned with sku, so each item only has one stock available. I use enumlist for sku in release table to allow the manager to select multiple skus in one ticket. 

Question is: How can I alter the number of the available stocks in inventory table once the ticket has been made with selected sku?

Please let me know if you need more info or pictures to reference the problem.

Thank you in advance.