MySQL从最后一天开始仅针对特定ID返回行

Question

I have 2 tables: 'clients' and 'orders', joined on the field 'client_id'.

CREATE TABLE IF NOT EXISTS `clients` (
  `client_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(120) NOT NULL,
  PRIMARY KEY (`client_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;

INSERT INTO `clients` (`client_id`, `name`) VALUES
(1, 'Ted Bundy'),
(2, 'Terry Towl');

CREATE TABLE IF NOT EXISTS `orders` (
  `order_id` int(11) NOT NULL AUTO_INCREMENT,
  `client_id` int(11) NOT NULL,
  `description` varchar(70) NOT NULL,
  `order_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`order_id`),
  KEY `client_id` (`client_id`),
  KEY `created` (`order_date`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=11 ;

INSERT INTO `orders` (`order_id`, `client_id`, `description`, `order_date`) VALUES
(1, 1, 'Shirt', '2015-12-02 01:14:01'),
(2, 2, 'Trousers', '2015-12-02 03:31:53'),
(3, 2, 'Underware', '2015-12-04 11:07:46'),
(4, 2, 'Hat', '2015-12-06 11:27:16'),
(5, 2, 'Scarf', '2015-12-07 00:14:31'),
(6, 2, 'Shirt', '2015-12-07 07:17:03'),
(7, 1, 'Shoes', '2015-12-09 16:23:20'),
(8, 1, 'Socks', '2015-12-11 11:40:16'),
(9, 1, 'Sweater', '2015-12-13 05:20:11'),
(10, 1, 'Shorts', '2015-12-13 12:41:31');

ALTER TABLE `orders`
ADD CONSTRAINT `orders_ibfk_1` 
FOREIGN KEY (`client_id`) 
REFERENCES `clients` (`client_id`) 
ON DELETE CASCADE 
ON UPDATE CASCADE;

I need to find the orders for the most recent day for a specific client_id, and only 1 client at a time

Example output for client_id 2

 client_id  |     name     |   description   |   order_date
-------------------------------------------------------------
      2     |  Terry Towl  |        Hat      |   2015-12-07
      2     |  Terry Towl  |       Scarf     |   2015-12-07

The issue is that we dont know the number of orders on that day, nor the date

The only way I can think to do this is to first query the date of the last order for a client, then to run another to find all records for that client on that date, however was hoping to be able to do this in one query.

Does anyone have an idea how to achieve this in one query?

Answer 1

Your idea is basically correct.

select *
from clients c join
     orders o
     on c.client_id = o.client_id
where c.client_id = $client_id and
      o.order_date = (select max(o2.order_date)
                      from orders o2
                      where o2.client_id = c.client_id
                     );