I'm creating a sales system that allows customers to place orders using a customer account. when a customer completes an order the number items in the order needs to be subtracted from the stock numbers of each of those items stored in the system.
This is for a school project and to meet the criteria this has to be done with a query, problem is I have no idea how to do this, honestly queries scare me.
What I have so far is zipped and attached,
The way my system works should be easy enough to understand, there are four linked tables that store information on customers, products and orders. What I'm really struggling to understand is how to take the values in the records in the Invoice-Product table and take them away from the stock numbers for the products in the products table. But only new orders should take away from the stock number when a new order is placed.
If possible I also need to be able to add stock numbers for example if a delivery comes in, and if it's similar enough could that also be done here? Or else I could ask for help on that in a different thread.
This is for a school project and to meet the criteria this has to be done with a query, problem is I have no idea how to do this, honestly queries scare me.
What I have so far is zipped and attached,
The way my system works should be easy enough to understand, there are four linked tables that store information on customers, products and orders. What I'm really struggling to understand is how to take the values in the records in the Invoice-Product table and take them away from the stock numbers for the products in the products table. But only new orders should take away from the stock number when a new order is placed.
If possible I also need to be able to add stock numbers for example if a delivery comes in, and if it's similar enough could that also be done here? Or else I could ask for help on that in a different thread.