The quantity sold to a customer is automatically deducted from the master product's quantity in hand. To see if the stock has been updated, first select the Master Product Information button from the toolbar at the bottom of the Main view — the first view of the application, we'll see the list of products stored in the MasterProduct entity. On selecting a master product, we'll see the page that displays the master product information. We will see that the quantity of the product is reduced by the quantity sold to the customer.
Let's complete the book with a small introduction of migrations and versioning. The concept of migrations and versioning is useful for us to understand in case we make some changes to our data model, that is, if we add or delete some attribute in any of the entities that we created in our application. Modification in the data model is usually required to meet future demands.