Question

我有一张表格显示以前的订单购买的每件商品都会在表格中添加为单独的行，请参阅下面的转储。

我的目标是每月显示每个订单的平均线数。为了获得平均线数，我需要将所购买的商品数量除以所下订单量。

我的查询目前为我提供了每月总计，而line_count返回了正确购买的商品数量，但我似乎无法返回已下订单的数量（在下面的转储中应该给出13）。我试过添加各种子查询，但我不知道该怎么做。有什么想法吗？

SELECT 
date, 
COUNT(orderno) AS line_count 
FROM `orders` 
AND 
date BETWEEN '2010-01-21' AND CURDATE() 
GROUP BY month(date), year(date) 
ORDER BY date

这是表格模式（为简洁起见而简化）

CREATE TABLE IF NOT EXISTS `orders` (
`id` int(11) NOT NULL AUTO_INCREMENT,
  `orderno` varchar(15) COLLATE utf8_unicode_ci NOT NULL,
  `date` date NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=22904 ;

--
-- Dumping data for table `orders`
--

INSERT INTO `orders` (`id`, `orderno`, `date`) VALUES
(1, 'rad10000', '2010-01-21'),
(2, 'rad10000', '2010-01-21'),
(3, 'rad10001', '2010-01-21'),
(4, 'rad10001', '2010-01-21'),
(5, 'rad10002', '2010-01-21'),
(6, 'rad10003', '2010-01-21'),
(8, 'rad10003', '2010-01-21'),
(9, 'rad10003', '2010-01-21'),
(10, 'rad10004', '2010-01-22'),
(11, 'rad10004', '2010-01-22'),
(12, 'rad10005', '2010-01-22'),
(13, 'rad10005', '2010-01-22'),
(14, 'rad10006', '2010-01-22'),
(15, 'rad10007', '2010-01-22'),
(16, 'rad10008', '2010-01-22'),
(17, 'rad10009', '2010-01-22'),
(18, 'rad10010', '2010-01-22'),
(19, 'rad10011', '2010-01-22'),
(20, 'rad10012', '2010-01-22');

Answer 1

哦，我明白了......

 SELECT YEAR(date)
      , MONTH(date) 
      , COUNT(*) line_count 
      , COUNT(DISTINCT orderno) orders_placed
   FROM orders
  WHERE date BETWEEN '2010-01-21' AND CURDATE() 
  GROUP 
     BY YEAR(date)
      , MONTH(date)  
  ORDER  
     BY date;

MySQL查询 - 每月订单的平均线数

1 个答案: