I developed this project to learn C# in February,2021. It is not work on your extising NorthWind Db. Because I edited the Northwind Db for this project. If you want to try it, you should restore my NorthWind.bak and edit the ConnectionString (FrmUserLogin._conString) in project. You can find it my Db in project files.
trkaydn/OrderControl
This project is a Windows Forms App and it is a little shopping app where using Northwind Db.
C#