如何计算每个小时数据库中的行数？

Question

在表中有两列：Datestamp像2012-12-16类型date和Timestamp像12:22:59类型time。 1 sql的特定日期每小时可以计算行数吗？在返回时，我需要获得24个数字。

Answer 1

事情是这样的：

SELECT COUNT(*) FROM your_table 
WHERE `Datestamp` = '2012-12-16' 
GROUP BY HOUR(`Timestamp`) 

Answer 2

SELECT datestamp as day, hour(timestamp) as hour, count(*) 
FROM your_table 
GROUP BY datestamp, hour(timestamp)