MySQL查詢 - 每月訂單的平均行數

我有一張顯示以前訂單的表格。
購買的每件商品都作爲表格中的單獨一行添加，請參閱下面的轉儲。MySQL查詢 - 每月訂單的平均行數

我的目標是顯示每月訂單的平均行數。爲了獲得平均數量的訂單，我需要將購買的物品數量除以訂單數量。

我的查詢目前給我的每月總數，line_count返回正確的購買物品數量，但我似乎無法返回放置的訂單數量（在下面的轉儲應該給13）。我曾嘗試添加各種子查詢，但我不知道如何去做這件事。有任何想法嗎？

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

這裏是（簡化爲清楚起見）

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');

來源

2013-03-21 monkey64

哦，我明白表模式...

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;

來源

2013-03-21 11:25:00 Strawberry

MySQL查詢 - 每月訂單的平均行數

回答

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