I need to enter product code and would like to display product description and price before record to the database.
How to do that?
Yes
Is this inside a form?
If you want to use data that’s been entered into a form before it’s been submitted, then you need to use a custom form.
or prefill some USC with the product ID
What do you mean prefill?
is all about how your app is created and data structured
I was assuming that the Product is selected inside the form…
i have the same feeling… but it might be some way to predict what will happen… 
like… choosing a product before going to the form
You meant I have to work in a product table in “This item” right? And add new row in another table?
you can get all product data iside the form using inline list and relations… just write product id to the user profile… and use relations there… form will pick up on that
My application is to scan barcode and display product description. I don’t want to swap many screens. Is it possible?
you don’t need to swap screens… use relations or User profile data