public List getAllExistsOrders(User user) {		
		String userId = user.getUserId();		
		//constructed by sql: select * from orders where user_id= user.userId
		//the object in the list will be Order.java
		List orderList = null; 	
		if(orderList != null) {			
			for(int i = 0, m = orderList.size(); i < m; i++) {				
				Order order = (Order) orderList.get(i);
				//constructed by sql: select * from order_items where 
                                                           //order_id=order.order_id
				//the object in the list will be OrderItem.java
				List orderItemList = null;
				order.setOrderItemList(orderItemList);
			}
		}		
		return orderList;
	}