Question

我有一个包含这些列的订单表：order_item order_category order_date 所以数据看起来像这样：

order_item  order_category   order_date 
1235        hardware         2014-01-07
1349        bedding          2014-01-07
1636        hardware         2014-01-08

等

大约有20个产品类别。此查询可以获取每天按类别排序的项目数：

 SELECT order_date, count(order_item) as num, order_category  
 FROM orders
 GROUP BY order_date, order_category

我想得到一个显示月份和每个类别的计数的结果，所以它看起来像这样：

 month    bedding  hardware etc
 2013-12  5        8
 2014-01  9        0

我可以用mysql做这个吗？

Answer 1

您还必须按年分组，否则您将获得每年“每个1月”的结果。

SELECT order_date, count(order_item) as num, order_category  
FROM orders
GROUP BY order_category, year(datefield), month(date field) desc;

一个简单的google for'mysql group by year and month'给出了这个好帖子......

Group by month and year in MySQL

Answer 2

试试这个：

   SELECT '2014-01' month , SUM(CASE WHEN order_category = 'hardware' 
                        THEN 1 ELSE 0 END )as hardware, 
                            SUM(CASE WHEN order_category = 'bedding' 
                        THEN 1 ELSE 0 END )as bedding
  FROM Table1
  WHERE MONTH(order_date) = 01 AND  year(order_date) = 2014

  UNION all 

  SELECT '2013-12' month , SUM(CASE WHEN order_category = 'hardware' 
                        THEN 1 ELSE 0 END )as hardware, 
                           SUM(CASE WHEN order_category = 'bedding' 
                        THEN 1 ELSE 0 END )as bedding
  FROM Table1
  WHERE MONTH(order_date) = 12 AND  year(order_date) = 2013

DEMO

MySQL按类别按月排序

2 个答案: