Question

我有一个名为startTime的字段，其类型为DATETIME。我每小时都有一些数据（每小时1行）。我想获取特定小时的最后7天（例如：01:00:00）。所以基本上，查询应该只返回7行。

我怎样才能在MySQL中做到这一点？

select traffic from incomingTraffic WHERE ...

示例数据：

+---------------------+---------------------+-----------+----------+
| startTime           | endTime             | component | traffic  |
+---------------------+---------------------+-----------+----------+
| 2015-05-01 00:00:00 | 2015-05-01 01:00:00 | rest      | 29090345 |
| 2015-05-01 01:00:00 | 2015-05-01 02:00:00 | rest      | 32224087 |
| 2015-05-01 02:00:00 | 2015-05-01 03:00:00 | rest      | 35165799 |
| 2015-05-01 03:00:00 | 2015-05-01 04:00:00 | rest      | 36903464 |
| 2015-05-01 04:00:00 | 2015-05-01 05:00:00 | rest      | 40394130 |
| 2015-05-01 05:00:00 | 2015-05-01 06:00:00 | rest      | 44874862 |
| 2015-05-01 06:00:00 | 2015-05-01 07:00:00 | rest      | 49988600 |
| 2015-05-01 07:00:00 | 2015-05-01 08:00:00 | rest      | 52240544 |
| 2015-05-01 08:00:00 | 2015-05-01 09:00:00 | rest      | 54517705 |
| 2015-05-01 09:00:00 | 2015-05-01 10:00:00 | rest      | 55277967 |
| 2015-05-01 10:00:00 | 2015-05-01 11:00:00 | rest      | 55285309 |
| 2015-05-01 11:00:00 | 2015-05-01 12:00:00 | rest      | 55572614 |
| 2015-05-01 12:00:00 | 2015-05-01 13:00:00 | rest      | 54507826 |
| 2015-05-01 13:00:00 | 2015-05-01 14:00:00 | rest      | 52430349 |
| 2015-05-01 14:00:00 | 2015-05-01 15:00:00 | rest      | 47084995 |
| 2015-05-01 15:00:00 | 2015-05-01 16:00:00 | rest      | 41671868 |
| 2015-05-01 16:00:00 | 2015-05-01 17:00:00 | rest      | 37492018 |
| 2015-05-01 17:00:00 | 2015-05-01 18:00:00 | rest      | 34391610 |
| 2015-05-01 18:00:00 | 2015-05-01 19:00:00 | rest      | 33814871 |
| 2015-05-01 19:00:00 | 2015-05-01 20:00:00 | rest      | 32466192 |
| 2015-05-01 20:00:00 | 2015-05-01 21:00:00 | rest      | 28703534 |
| 2015-05-01 21:00:00 | 2015-05-01 22:00:00 | rest      | 25564237 |
| 2015-05-01 22:00:00 | 2015-05-01 23:00:00 | rest      | 23209539 |
| 2015-05-01 23:00:00 | 2015-05-02 00:00:00 | rest      | 24853381 |
| 2015-05-02 00:00:00 | 2015-05-02 01:00:00 | rest      |    24090 |
| 2015-05-02 00:00:00 | 2015-05-02 01:00:00 | rest      | 26848485 |
| 2015-05-02 01:00:00 | 2015-05-02 02:00:00 | rest      | 28507177 |
| 2015-05-02 02:00:00 | 2015-05-02 03:00:00 | rest      | 29970856 |
| 2015-05-02 03:00:00 | 2015-05-02 04:00:00 | rest      | 30607213 |
| 2015-05-02 04:00:00 | 2015-05-02 05:00:00 | rest      | 34005454 |
| 2015-05-02 05:00:00 | 2015-05-02 06:00:00 | rest      | 38241748 |
| 2015-05-02 06:00:00 | 2015-05-02 07:00:00 | rest      | 42154837 |
| 2015-05-02 07:00:00 | 2015-05-02 08:00:00 | rest      | 44181502 |
| 2015-05-02 08:00:00 | 2015-05-02 09:00:00 | rest      | 45787319 |
| 2015-05-02 09:00:00 | 2015-05-02 10:00:00 | rest      | 47283634 |
| 2015-05-02 10:00:00 | 2015-05-02 11:00:00 | rest      | 47328065 |
| 2015-05-02 11:00:00 | 2015-05-02 12:00:00 | rest      | 47370131 |
| 2015-05-02 12:00:00 | 2015-05-02 13:00:00 | rest      | 46298305 |
| 2015-05-02 13:00:00 | 2015-05-02 14:00:00 | rest      | 43894081 |
| 2015-05-02 14:00:00 | 2015-05-02 15:00:00 | rest      | 40307217 |
| 2015-05-02 15:00:00 | 2015-05-02 16:00:00 | rest      | 35481808 |
| 2015-05-02 16:00:00 | 2015-05-02 17:00:00 | rest      | 32316694 |
| 2015-05-02 17:00:00 | 2015-05-02 18:00:00 | rest      | 30426755 |
| 2015-05-02 18:00:00 | 2015-05-02 19:00:00 | rest      | 29809260 |
| 2015-05-02 19:00:00 | 2015-05-02 20:00:00 | rest      | 28466543 |
| 2015-05-02 20:00:00 | 2015-05-02 21:00:00 | rest      | 25392149 |
| 2015-05-02 21:00:00 | 2015-05-02 22:00:00 | rest      | 21182582 |
| 2015-05-02 22:00:00 | 2015-05-02 23:00:00 | rest      | 20954845 |

Answer 1

这个问题比它看起来更棘手，因为它取决于数据的更新方式以及OP在过去7天内的真实含义＆＃34;。

如果您想要相对于当前日期的最后7天，请使用：

WHERE hour(startTime) = 7 AND
      startTime >= date_sub(CURDATE(), interval 7 day)

现在，这可能会让您获得7天或8天的时间，具体取决于数据的更新方式和当前时间。您可以添加ORDER BY startTime DESC LIMIT 7以获得7天。

如果您想在表格中显示最近7天，请尝试以下方法：

SELECT traffic
FROM incomingTraffic
WHERE hour(startTime) = 7
ORDER BY startTime DESC
LIMIT 7;

这将获得最近7天的数据。但是，如果您有一个大表，这可能是低效的。在WHERE上使用startTime子句可以提高查询效率。

Answer 2

除了数据应该小于7天的情况外，添加条件hour()=1

SELECT traffic FROM incomingTraffic 
WHERE hour(startTime)=1 AND startTime>ADDDATE(NOW(), -7);

抱歉，花了一些时间收集其他位并让它们正确; - ）

Answer 3

您可以使用DATE_SUB operation获得7天，并将小时与HOUR()相匹配，从而为您提供日期的小时部分。

SELECT startTime, traffic FROM incomingTraffic 
WHERE
  startTime > DATE_SUB('2015-05-01', INTERVAL 7 DAY) 
  AND HOUR(startTime) = 1;

请注意，我没有NOW()，因为您的示例数据已经过去了。另请注意，您应首先检查日期范围，然后执行小时比较，因为这样会更便宜，因为mysql需要进行转换以检查小时。

查询MYSQL特定小时的最近7天数据

3 个答案: