static void deleteAll() { using (EFCoreContext db = new EFCoreContext()) { db.RemoveRange(db.Departments.ToList()); db.RemoveRange(db.Employees.ToList()); db.RemoveRange(db.Regions.ToList()); db.RemoveRange(db.Territories.ToList()); db.RemoveRange(db.SalesPersons.ToList()); db.SaveChanges(); } }