mysql - 如何根据时间(月、年)统计记录？

Question

我有一个表 (myItems)，其中包含一个项目“id”和“date”。现在我想读出，每个月有多少项目(我也想区分2013年10月和2014年10月)。

我开始于:

SELECT Count(okt.id) AS Oktober, Count(nov.id) AS November
FROM    `myItems` as okt,
        `myItems` as nov    
WHERE (okt.date between '2013-10-01' and '2013-10-31') 
   OR (nov.date between '2013-11-01' and '2013-11-30')

但是它打印出一个大得离谱的数字。我做错了什么？

Answer 1

试试这个。这会将数据分成几个月，然后执行 COUNT :

SELECT SUM(CASE WHEN MONTH(date) = 10 THEN 1 ELSE 0 END) AS Oktober
     , SUM(CASE WHEN MONTH(date) = 11 THEN 1 ELSE 0 END) AS November
FROM    `myItems`

演示:SQL Fiddle

---

集成了 YEAR:

SELECT 2013 as Year
     , SUM(CASE WHEN MONTH(date) = 10 THEN 1 ELSE 0 END) AS Oktober
     , SUM(CASE WHEN MONTH(date) = 11 THEN 1 ELSE 0 END) AS November
FROM    `myItems`
WHERE YEAR(date) = 2013
UNION ALL
SELECT 2014 as Year
     , SUM(CASE WHEN MONTH(date) = 10 THEN 1 ELSE 0 END) AS Oktober
     , SUM(CASE WHEN MONTH(date) = 11 THEN 1 ELSE 0 END) AS November
FROM    `myItems`
WHERE YEAR(date) = 2014;
;

演示:Fiddle

---

灵感来自@user77318

SELECT YEAR(date) as Year, month(date) as month, count(id) as count 
FROM myItems 
GROUP BY YEAR(date), MONTH(date);

个人推荐这个，比较漂亮。然后你就可以在应用层做所有的展示工作了。