Variables in Database

Hi everyone,

I’m having some trouble with an app I’m creating to log the inventory for different stores of a local retailer. The issue that I’m running into is I don’t understand how to reference the relationship between the items and the stores.

Each store carries around 90 different items. I want to use a barcode scanner to which will pull out the UPC code for each item when scanned in the store, and have my app use that UPC number to lookup the information for that item so the count can be updated.

Where I’m getting confused is: I don’t understand how to have my database of the UPC codes for the items, AND how to have each store be able to count their items without changing the counts for the other stores. I tried a many-to-many relationship, but it doesn’t seem like it’s working.

Can someone help explain how I can have the count for each item be unique to each store without having to manually create each item entry in each store entry?

Thank you and sorry if this is a silly question! I’m new to this