98 lines
2.9 KiB
Markdown
98 lines
2.9 KiB
Markdown
Use the `SELECT` statement to query data from an InfluxDB measurement.
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The `SELECT` clause is required when querying data in SQL.
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- [Syntax](#syntax)
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- [Examples](#examples)
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### Syntax
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```sql
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SELECT a, b, "time" FROM <measurement>
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```
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The SELECT clause supports the following:
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- `SELECT *` - return all tags, fields and timestamps.
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- `SELECT DISTINCT` to return all distinct (different) values.
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- `SELECT <"field" or "tag">` - returns a specified field or tag.
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- `SELECT <"field" or "tag">, <"field" or "tag">` - returns more than one tag or field.
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- `SELECT <"field"> AS a `- return the field as the alias.
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## Examples
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The following examples use data from the NOAA database.
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To download the NOAA test data see [NOAA water sample data](/influxdb/v2/reference/sample-data/#noaa-water-sample-data).
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### Select all fields and tags from a measurement
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```sql
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SELECT * FROM h2o_feet LIMIT 10
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```
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{{< expand-wrapper >}}
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{{% expand "View example results" %}}
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| level description | location | time | water_level |
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| :------------------------ | :----------- | :----------------------- | :---------- |
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| at or greater than 9 feet | coyote_creek | 2019-09-01T00:00:00.000Z | 9.126144144 |
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| at or greater than 9 feet | coyote_creek | 2019-09-01T00:06:00.000Z | 9.009 |
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| between 6 and 9 feet | coyote_creek | 2019-09-01T00:12:00.000Z | 8.862 |
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| between 6 and 9 feet | coyote_creek | 2019-09-01T00:18:00.000Z | 8.714 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Select specific tags and fields from a measurement
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```sql
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SELECT "location", "water_level" FROM "h2o_feet"
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```
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{{< expand-wrapper >}}
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{{% expand "View example results" "1" %}}
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| location | water_level |
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| :----------- | :---------- |
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| coyote_creek | 9.126144144 |
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| coyote_creek | 9.009 |
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| coyote_creek | 8.862 |
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| coyote_creek | 8.714 |
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| coyote_creek | 8.547 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Select a field, tag and timestamp from a measurement
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```sql
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SELECT "water_level", "location", "time" FROM "h2o_feet"
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```
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{{< expand-wrapper >}}
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{{% expand "View example results" "2" %}}
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| location | time | water_level |
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| :----------- | :----------------------- | :---------- |
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| coyote_creek | 2019-08-20T00:00:00.000Z | 8.638 |
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| coyote_creek | 2019-08-20T00:06:00.000Z | 8.658 |
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| coyote_creek | 2019-08-20T00:12:00.000Z | 8.678 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Select a field and perform basic arithmetic
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The following query takes the value of water_level, multiplies it by 3 and adds 5 to the result.
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```sql
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SELECT ("water_level" * 3) + 5 FROM "h2o_feet"
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```
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{{< expand-wrapper >}}
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{{% expand "View example results" "3" %}}
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| water_level |
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| :----------------- |
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| 30.128 |
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| 30.641000000000002 |
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| 31.142000000000003 |
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| 31.586 |
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| 32.027 |
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| 32.378432432 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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