Documentation

UNION clause

Limited availability

InfluxDB Clustered is currently only available to a limited group of InfluxData customers. If interested in being part of the limited access group, please contact the InfluxData Sales team.

The UNION clause combines the results of two or more SELECT statements into a single result set. By default, UNION only keeps unique rows. To keep all rows, including duplicates, use UNION ALL.

When using the UNION clause:

  • The number of columns in each result set must be the same.
  • Columns must be in the same order and of the same or compatible data types.

Syntax

SELECT expression[,...n]
FROM measurement_1
UNION [ALL]
SELECT expression[,...n]
FROM measurement_2

Examples

Union results from different measurements

(
  SELECT
    'h2o_pH' AS measurement,
    time,
    "pH" AS "water_pH"
  FROM "h2o_pH"
  LIMIT 4
)
UNION
(
  SELECT
    'h2o_quality' AS measurement,
    time,
    index
  FROM h2o_quality
  LIMIT 4
)

View example results

Return the highest and lowest three results in a single result set

The following example uses the sample data set provided in Get started with InfluxDB tutorial.

(
  SELECT
    'low' as type,
    time,
    co
  FROM home
  ORDER BY co ASC
  LIMIT 3
)
UNION 
(
  SELECT
    'high' as type,
    time,
    co
  FROM home
  ORDER BY co DESC
  LIMIT 3
)

View example results

Union query results with custom data

The following example uses the sample data set provided in Get started with InfluxDB tutorial. It also uses the table value constructor to build a table with custom data.

SELECT *
FROM home
WHERE
  time >= '2022-01-01T08:00:00Z'
  AND time <= '2022-01-01T12:00:00Z'
UNION
SELECT * FROM
  (VALUES (0, 34.2, 'Bedroom', 21.1, '2022-01-01T08:00:00Z'::TIMESTAMP),
          (0, 34.5, 'Bedroom', 21.2, '2022-01-01T09:00:00Z'::TIMESTAMP),
          (0, 34.6, 'Bedroom', 21.5, '2022-01-01T10:00:00Z'::TIMESTAMP),
          (0, 34.5, 'Bedroom', 21.8, '2022-01-01T11:00:00Z'::TIMESTAMP),
          (0, 33.9, 'Bedroom', 22.0, '2022-01-01T12:00:00Z'::TIMESTAMP)
  ) newRoom(co, hum, room, temp, time)
ORDER BY room, time

View example results


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Introducing InfluxDB Clustered

A highly available InfluxDB 3.0 cluster on your own infrastructure.

InfluxDB Clustered is a highly available InfluxDB 3.0 cluster built for high write and query workloads on your own infrastructure.

InfluxDB Clustered is currently in limited availability and is only available to a limited group of InfluxData customers. If interested in being part of the limited access group, please contact the InfluxData Sales team.

Learn more
Contact InfluxData Sales

The future of Flux

Flux is going into maintenance mode. You can continue using it as you currently are without any changes to your code.

Flux is going into maintenance mode and will not be supported in InfluxDB 3.0. This was a decision based on the broad demand for SQL and the continued growth and adoption of InfluxQL. We are continuing to support Flux for users in 1.x and 2.x so you can continue using it with no changes to your code. If you are interested in transitioning to InfluxDB 3.0 and want to future-proof your code, we suggest using InfluxQL.

For information about the future of Flux, see the following: