How to create condition on an action?

[hungpuiki]

1. I am writing an inventory management app.

2. if the user created a transaction by clicking “save” in the form “Transaction”. The system should do an auto action to save this transaction entry in the “Transaction” table. At the same time, the system should do an ‘Action’ to update the total quantity of that specific product in another table.

3. In this ‘Action’, i want to search if there is already a row in the table for that product. If there is, the system should change the quantity accordingly. If there isn’t, the system should create a new row. Can appsheet do this?

Thx!