MySQL 每 15 分钟对纪元时间戳进行分组

Question

我有一个数据库，它以相当高的频率收集一些数据并记录每个条目的时间戳（存储为纪元时间，而不是 mysql 日期时间）。例如

timestamp               rssi    sender
-------------------------------------------
1592353967.171600       -67     9EDA3DBFFE15
1592353967.228000       -67     9EDA3DBFFE15
1592353967.282900       -62     E2ED2569BE2
1592353971.892600       -67     9EDA3DBFFE15
1592353973.962900       -61     2ADE2E4597B2
...

我的目标是能够在 15 分钟的时间间隔内获得所有行的计数，经过研究可以通过 GROUP BY 获得。理想情况下，最终输出应该是这样的

timestamp               count
------------------------------
1592352000 (8:00pm EST)   38    
1592352900 (8:15pm EST)   22
1592353800 (8:30pm EST)   0 <----- Important, must include periods with 0 entries
1592354700 (8:45pm EST)   61
...

我主要有两个问题： 1.能够在结果中显示时间戳间隔 2.显示时间段内0行的区间

我目前的尝试是这样的，而且是对的，因为那个时间段的数据其实是正确的

 Showing rows 0 - 23 (24 total, Query took 0.0264 seconds.)

SELECT count(*) AS total, MINUTE(FROM_UNIXTIME(timestamp)) AS minute
FROM requests
WHERE timestamp >= 1592352000 AND timestamp < (1592352000 + 3600)  
GROUP BY MINUTE(FROM_UNIXTIME(timestamp))

total   minute  
55  32  
89  33  
64  34  
55  35  
87  36  
82  37  
90  38  
69  39  
74  40  
47  41  
89  42  
53  43  
71  44  
87  45  
72  46  
83  47  
86  48  
83  49  
113 50  
76  51  
77  52  
88  53  
81  54  
28  55

此数据是正确的，但有些时段未在此处显示（该小时的前 30 分钟没有数据，因此第一个 minute 条目从 32 开始）。还尝试使用

每 15 分钟获取一次

SELECT count(*) AS total, MINUTE(FROM_UNIXTIME(timestamp)) AS minute
FROM requests
WHERE timestamp >= 1592352000 AND timestamp < (1592352000 + 3600)  
GROUP BY MINUTE(FROM_UNIXTIME(timestamp)) DIV 15

#1055 - Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'wave_master.requests.timestamp' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

如有任何帮助，我们将不胜感激。

Answer 1

您可以使用 "numbers" table 在一小时 (0-3) 内生成 15 分钟的时间段，然后 LEFT JOIN 根据您的计数，按 15 分组分钟周期，使用 COALESCE 将 NULL 值替换为 0:

SELECT periods.period * 900 + 1592352000 AS timestamp,
       FROM_UNIXTIME(periods.period * 900 + 1592352000) AS time,
       COALESCE(counts.total, 0) AS total
FROM (
  SELECT 0 period
  UNION ALL SELECT 1 
  UNION ALL SELECT 2
  UNION ALL SELECT 3
) periods
LEFT JOIN (
  SELECT (timestamp - 1592352000) DIV 900 AS period,
         COUNT(*) AS total
  FROM requests
  WHERE timestamp >= 1592352000 AND timestamp < 1592352000 + 3600
  GROUP BY period
) counts ON counts.period = periods.period

输出（对于您问题中的数据加上其他几个值）：

timestamp   time                    total
1592352000  2020-06-17 00:00:00     1
1592352900  2020-06-17 00:15:00     1
1592353800  2020-06-17 00:30:00     5
1592354700  2020-06-17 00:45:00     0

Demo on dbfiddle

MySQL 每 15 分钟对纪元时间戳进行分组

MySQL Group Epoch Timestamp by Every 15 Minutes

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