134 lines
3.8 KiB
Markdown
134 lines
3.8 KiB
Markdown
Use InfluxQL date and time functions to perform time-related operations.
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- [now()](#now)
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- [time()](#time)
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- [tz()](#tz)
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## now()
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Returns the current system time (UTC).
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_Supported only in the [`WHERE` clause](/influxdb/version/reference/influxql/where/)._
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```sql
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now()
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```
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## time()
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Used in the [`GROUP BY` clause](/influxdb/version/reference/influxql/group-by/)
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to group data into time-based intervals, also known as "windows", using the specified interval.
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Timestamps in the `time` column are updated to the start boundary of the window
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they're in and grouped by `time`.
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Windows use preset round-number boundaries based on the specified interval that
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are independent of time conditions in the
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[`WHERE` clause](/influxdb/version/reference/influxql/where/).
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This operation can be used to do the following:
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- Downsample data by aggregating multiple points in each window into a single
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point per window.
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- Normalize irregular time series data to occur at regular intervals.
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_Supported only in the [`GROUP BY` clause](/influxdb/version/reference/influxql/group-by/)._
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```sql
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time(interval[, offset])
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```
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#### Arguments
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- **interval**: Duration literal that specifies the window interval.
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- **offset**: Duration literal that shifts preset time boundaries forward or backward.
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Can be positive or negative. _Default is `0s`._
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##### Examples {#time-examples}
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{{< expand-wrapper >}}
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{{% expand "Downsample data into time-based intervals" %}}
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The following example uses the
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[Bitcoin price sample dataset](/influxdb/version/reference/sample-data/#bitcoin-price-data).
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```sql
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SELECT
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MEAN(price)
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FROM bitcoin
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WHERE
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code = 'GBP'
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AND time >= '2023-05-01T00:00:00Z'
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AND time < '2023-05-15T00:00:00Z'
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GROUP BY time(2d)
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```
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{{% influxql/table-meta %}}
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name: bitcoin
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{{% /influxql/table-meta %}}
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| time | mean |
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| :------------------- | -----------------: |
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| 2023-05-01T00:00:00Z | 23680.120447159094 |
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| 2023-05-03T00:00:00Z | 24048.71484033149 |
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| 2023-05-05T00:00:00Z | 24461.9194901099 |
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| 2023-05-07T00:00:00Z | 23796.43801933702 |
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| 2023-05-09T00:00:00Z | 23118.709889285707 |
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| 2023-05-11T00:00:00Z | 22465.008364444446 |
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| 2023-05-13T00:00:00Z | 22499.464763186803 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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## tz()
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Applies a timezone offset to timestamps in query results.
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Offsets include any seasonal offset such as Daylight Savings Time (DST) or
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British Summer Time (BST).
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_Supported only in the [time zone clause](/influxdb/version/reference/influxql/time-and-timezone/#time-zone-clause)._
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```sql
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tz(time_zone)
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```
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#### Arguments
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- **time_zone**: Timezone string literal to adjust times to.
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Uses timezone names defined in the
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[Internet Assigned Numbers Authority time zone database](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones#List).
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#### Examples {#tz-examples}
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{{< expand-wrapper >}}
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{{% expand "Return the UTC offset for Chicago's time zone" %}}
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The following example uses the
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[Get started home sensor sample dataset](/influxdb/version/reference/sample-data/#get-started-home-sensor-data).
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{{% influxdb/custom-timestamps %}}
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```sql
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SELECT *
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FROM home
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WHERE
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room = 'Kitchen'
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AND time >= '2022-01-01T08:00:00Z'
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AND time <= '2022-01-01T12:00:00Z'
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tz('America/Chicago')
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```
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{{% influxql/table-meta %}}
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name: home
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{{% /influxql/table-meta %}}
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| time | co | hum | room | temp |
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| :------------------------ | --: | ---: | :------ | ---: |
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| 2022-01-01T02:00:00-06:00 | 0 | 35.9 | Kitchen | 21 |
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| 2022-01-01T03:00:00-06:00 | 0 | 36.2 | Kitchen | 23 |
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| 2022-01-01T04:00:00-06:00 | 0 | 36.1 | Kitchen | 22.7 |
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| 2022-01-01T05:00:00-06:00 | 0 | 36 | Kitchen | 22.4 |
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| 2022-01-01T06:00:00-06:00 | 0 | 36 | Kitchen | 22.5 |
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{{% /influxdb/custom-timestamps %}}
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{{% /expand %}}
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{{< /expand-wrapper >}}
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