influxdb select mean

这是一个 InfluxDB 查询语句，用于查询某个时间段内某个字段的平均值。具体语法为：

SELECT MEAN(field_key) FROM measurement WHERE time >= start_time AND time <= end_time

其中，`field_key` 是要计算平均值的字段名，`measurement` 是要查询的表名，`start_time` 和 `end_time` 分别是查询的起始时间和结束时间。

例如，要查询名为 `cpu_usage` 的表在过去一小时内 `usage_percent` 字段的平均值，可以使用以下语句：

SELECT MEAN(usage_percent) FROM cpu_usage WHERE time >= now() - 1h

相关问题

influxdb select aggregation

In InfluxDB, you can use the SELECT statement to perform aggregations on data. The SELECT statement allows you to retrieve and manipulate data from your InfluxDB database.

To perform aggregations, you can use various functions available in InfluxDB. These functions include:

1. MEAN: Calculates the arithmetic mean of the selected field over a specified time range.
2. SUM: Calculates the sum of the selected field over a specified time range.
3. COUNT: Counts the number of data points in the selected field over a specified time range.
4. MEDIAN: Calculates the median value of the selected field over a specified time range.
5. MAX: Retrieves the maximum value of the selected field over a specified time range.
6. MIN: Retrieves the minimum value of the selected field over a specified time range.

Here's an example of using the MEAN function to calculate the average temperature over a 5-minute time interval:

SELECT MEAN("temperature") FROM "measurement" WHERE time >= now() - 5m GROUP BY time(1m)

This query selects the "temperature" field from the "measurement" measurement and calculates the mean value over a 5-minute time interval. The result is grouped by 1-minute intervals.

You can modify this query according to your specific requirements and use other aggregation functions as needed.

influxdb2执行select语句

InfluxDB 2是一款开源的时间序列数据库，用于存储和查询测量值数据。在InfluxDB 2中，执行`SELECT`语句的基本结构通常是这样的：

SELECT [MEASUREMENTS[, MEASUREMENTS...]] [GROUP BY [{FIELD}, {FIELD}...]]
[WHERE condition]
[ORDER BY FIELD [ASC|DESC], [FIELD] [ASC|DESC]...]
[LIMIT number]
OFFSET number

- `SELECT`: 声明你要查询哪些数据（默认会返回所有数据）。
- `MEASUREMENTS`: 指定你想要查询的具体测量点名称，可以指定多个。
- `GROUP BY`: 分组查询结果，常见于聚合操作，如计算平均值、总和等。
- `WHERE`: 过滤条件，可以根据标签键值对或时间范围筛选数据。
- `ORDER BY`: 设置结果按照特定字段排序。
- `LIMIT`: 可限制查询返回的数据量。
- `OFFSET`: 开始偏移位置，用于分页查询。

例如，如果你想知道名为"cpu_usage"的测量点在过去一小时内的平均CPU使用率，并按时间降序排列，你可以使用如下命令：

SELECT mean(cpu) FROM cpu_usage WHERE time > now() - 1h ORDER BY time DESC LIMIT 1;