MySQL / PHP组按小时，然后在每个组的计数＃ [英] MySQL/PHP Group by hour of day then Count # in each group

问题描述

我目前的任务有困难。

I am having difficulity with my current task. It deals with displaying the most popular time of day for room rental.

我有一个大型数据库（25万个条目），输入日期/时间存储为日期时间。
例如：

I have a large database (250,000+ entries), with entry dates/times stored as datetime. Example:

2015-06-10 19:30:15
2015-06-10 18:30:15
2015-06-10 14:03:15
2015-06-09 16:30:15
2015-06-09 14:30:15
2015-06-09 14:50:15
2015-06-08 13:30:15
2015-06-08 14:05:15

我需要做的是按1小时的间隔进行分组，然后返回每个间隔中条目数的计数。

What I need to do, is group by 1 hour intervals, then return the count of number of entries in each interval.

示例（不反映第一个示例集中的数据）：

Example (Does not reflect data in first example set):

09:01 - 10:00 = 2
10:01 - 11:00 = 3
10:01 - 12:00 = 6
12:01 - 13:00 = 8
13:01 - 14:00 = 5

我能做到这一点的唯一方法是创建一个sql查询

The only way I have been able to do this, is create a sql query for each interval, but I am very dissatisfied doing it in that manor.

任何人都可以帮助我理解如何更好地完成这种类型的查询？

Can anyone help me understand how to better accomplish this type of query?

PS

推荐答案

Select date_format(yourdatetime, '%H'), count(*)
From yourtable
Group by date_format(yourdatetime, '%H');

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