Find a Product with Barcode

I want to find the Product using the Barcode Please help:

1) Column/table/etc: Order Table has Barcode column named Bc of type Text and I have put a tic mark on Scan to make it scannable and Stock Item Name named as SIName of type Ref. which is referring to Stock Item Table which has the Products Listed.

2) Expected behavior: When we scan the Barcode it should look at the StockItem table and if it finds the Product it should show it in the SIName column in the form and if it cannot find that Barcode it should let us choose the StockItem from the Dropdown list.