无论时区如何,都将MySQL日期时间分组为间隔

Question

之前已经问过这个问题,但我面临的问题略有不同.

我有一个表记录事件并存储他们的时间戳(作为日期时间).我需要能够将时间分解成块并获得在该间隔中发生的事件的数量.间隔可以是自定义的(比如5分钟到1小时甚至更长).

显而易见的解决方案是将datetime转换为unix_timestamp,将其除以间隔中的秒数,取其底层函数并将其乘以秒数.最后将unix_timestamp转换回日期时间格式.

这适用于小间隔.

select 
from_unixtime(floor(unix_timestamp(event.timestamp)/300)*300) as start_time,
count(*) as total 
from event 
where timestamp>='2012-08-03 00:00:00' 
group by start_time;

这给出了正确的输出

+---------------------+-------+
| start_time          | total |
+---------------------+-------+
| 2012-08-03 00:00:00 |    11 |
| 2012-08-03 00:05:00 |     4 |
| 2012-08-03 00:10:00 |     4 |
| 2012-08-03 00:15:00 |     7 |
| 2012-08-03 00:20:00 |     8 |
| 2012-08-03 00:25:00 |     1 |
| 2012-08-03 00:30:00 |     1 |
| 2012-08-03 00:35:00 |     3 |
| 2012-08-03 00:40:00 |     3 |
| 2012-08-03 00:45:00 |     5 |
~~~~~OUTPUT SNIPPED~~~~~~~~~~~~

但如果我把间隔增加到1小时(3600秒)

mysql> select from_unixtime(floor(unix_timestamp(event.timestamp)/3600)*3600) as start_time, count(*) as total from event where timestamp>='2012-08-03 00:00:00' group by start_time;
+---------------------+-------+
| start_time          | total |
+---------------------+-------+
| 2012-08-02 23:30:00 |    35 |
| 2012-08-03 00:30:00 |    30 |
| 2012-08-03 01:30:00 |    12 |
| 2012-08-03 02:30:00 |    18 |
| 2012-08-03 03:30:00 |    12 |
| 2012-08-03 04:30:00 |     4 |
| 2012-08-03 05:30:00 |     3 |
| 2012-08-03 06:30:00 |    13 |
| 2012-08-03 07:30:00 |   269 |
| 2012-08-03 08:30:00 |   681 |
| 2012-08-03 09:30:00 |  1523 |
| 2012-08-03 10:30:00 |   911 |
+---------------------+-------+

据我所知,未正确设置边界的原因是unix_timestamp会将时间从我的本地时区(GMT + 0530)转换为UTC,然后输出数值.

所以像2012-08-03 00:00:00这样的值实际上是2012-08-02 18:30:00.划分和使用楼层会将分钟部分设置为00.但是当我使用from_unixtime时,它会将其转换回GMT + 0530,因此我会在30分钟内开始间隔.

无论时区如何,如何确保查询正常工作？我使用MySQL 5.1.52所以to_seconds()不可用

编辑: 无论间隔(可以是小时,分钟,天),查询也应该正确触发.一般的解决方案将不胜感激

Answer 1

您可以使用TIMESTAMPDIFF按时间间隔分组:

对于指定的小时间隔,您可以使用:

SELECT   '2012-08-03 00:00:00' + 
         INTERVAL FLOOR(TIMESTAMPDIFF(HOUR, '2012-08-03 00:00:00', timestamp) / <n>) * <n> HOUR AS start_time,
         COUNT(*) AS total 
FROM     event 
WHERE    timestamp >= '2012-08-03 00:00:00'
GROUP BY start_time

用2012-08-03 00:00:00最小输入日期替换出现的情况.

<n>是您指定的小时间隔(2每小时,3每小时等),您可以在几分钟内执行相同操作:

SELECT   '2012-08-03 00:00:00' + 
         INTERVAL FLOOR(TIMESTAMPDIFF(MINUTE, '2012-08-03 00:00:00', timestamp) / <n>) * <n> MINUTE AS start_time,
         COUNT(*) AS total 
FROM     event 
WHERE    timestamp >= '2012-08-03 00:00:00'
GROUP BY start_time

凡<n>在你指定的时间间隔分钟(每45分钟,90分钟等).

确保您将最小输入日期(在此示例中2012-08-03 00:00:00)作为第二个参数传递给TIMESTAMPDIFF.

编辑:如果您不想担心在TIMESTAMPDIFF功能中选择哪个间隔单位,那么当然只需要按秒间隔(300 = 5分钟,3600 = 1小时,7200 = 2小时等)

SELECT   '2012-08-03 00:00:00' + 
         INTERVAL FLOOR(TIMESTAMPDIFF(SECOND, '2012-08-03 00:00:00', timestamp) / <n>) * <n> SECOND AS start_time,
         COUNT(*) AS total 
FROM     event 
WHERE    timestamp >= '2012-08-03 00:00:00'
GROUP BY start_time

编辑2:要解决有关减少语句中您必须通过最小参数日期的区域数量的注释,您可以使用:

SELECT   b.mindate + 
         INTERVAL FLOOR(TIMESTAMPDIFF(SECOND, b.mindate, timestamp) / <n>) * <n> SECOND AS start_time,
         COUNT(*) AS total 
FROM     event 
JOIN     (SELECT '2012-08-03 00:00:00' AS mindate) b ON timestamp >= b.mindate
GROUP BY start_time

只需将最小日期时间参数传递到join子选择中.

您甚至可以在连接子选择中为秒间隔(例如3600)创建第二列,并将列命名为secinterval...然后将<n>'s 更改为b.secinterval,所以您只需要传递最小日期参数和间隔一次.

SQLFiddle演示