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();
}
}