public NorthwindUnitOfWork(string connectionString)
{
Customers = new CustomersRepository(connectionString);
Orders = new OrdersRepository(connectionString);
OrderDetails = new OrderDetailsRepository(connectionString);
Users = new UserRepository(connectionString);
Products = new ProductsRepository(connectionString);
Suppliers = new SuppliersRepository(connectionString);
Clientes = new ClientesRepository(connectionString);
Contratistas = new ContratistasRepository(connectionString);
Contratos = new ContratosRepository(connectionString);
Lugares = new LugaresRepository(connectionString);
Servicios = new ServiciosRepository(connectionString);
}