.net core 3.1 code first entity framework code code example
Example 1: asp.net core entity framework database first
PM> Scaffold-DbContext "Server=.\SQLExpress;Database=SchoolDB;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models
Example 2: c# .net core entity framework
//ref https://softchris.github.io/pages/dotnet-orm.html#why-orm