Microsoft Access Queries

Hello

I am working on a project for my Data Management class in university, and I am required to create a database from scratch and show the relationships and make it work.

I am currently working on a Vending Machine database, where my tables are as follows: Customer, Item, Order, Supplier, Manufacturer. I have made all the relationships that are needed for all the tables to be able to communicate with one another.

My questions are as follows:
- How can I make a transaction occur in Access?
- How can I automatically update my 'Quantity' field after each transaction that has been made?
- How can I make my database flag or warn the Suppliers whenever the 'Quantity' field reaches 50% of the initial quantity? (For example: I have 10 KitKats in the vending machine, whenever a customer buys 1 KitKat, obviously the quantity of the KitKat will reduce. I want my database to warn me when the amount of KitKats reaches 5 and I want it to automatically send a request to the supplier to get more KitKats.)
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I am relatively new to this course and to this major and I am in desperate need of help.

Thank you
Regards