按时间分组，其中时间是在MySQL日期列？

Question

ID   Date 
1   2013-01-11 00:57:25 
2   2013-02-01 02:17:05 
3   2013-02-05 03:12:23 
4   2013-02-17 10:17:02 
5   2013-02-19 11:27:25 
6   2013-02-27 13:42:13 
7   2013-03-09 15:57:25 
8   2013-03-12 16:00:00 
9   2013-04-10 19:39:18 
10   2013-05-16 20:46:38 

我希望Group ID根据时间在这张表中。请记住日期在一列中，所以我可以根据不同的时间从日期列和组中只取时间。

像我想ID从一组00:00:00 to 12:00:00和12:00:00 to 24:00:00在另一组在mysql。

Answer 1

SELECT 
CASE WHEN TIME(`Date`) BETWEEN '00:00:00' AND '12:00:00' THEN 'early' ELSE 'late' END AS myTime, 
COUNT(*) 
FROM yourTable 
GROUP BY myTime 

您还可以添加多个 “组” 轻松：

SELECT 
CASE WHEN TIME(`Date`) BETWEEN '00:00:00' AND '03:00:00' THEN '0-3' 
CASE WHEN TIME(`Date`) BETWEEN '03:00:01' AND '06:00:00' THEN '3-6' 
ELSE 'later' END AS myTime, 
COUNT(*) 
FROM yourTable 
GROUP BY myTime 

Answer 2

提示：

SELECT HOUR(Date), COUNT(*) 
FROM your_table 
GROUP BY HOUR(Date);