Regular expressions

SELECT /l/ FROM "h2o_feet" LIMIT 1

Output:

The query selects all field keys and tag keys that include an l. Note that the regular expression in the SELECT clause must match at least one field key in order to return results for a tag key that matches the regular expression.

Currently, there is no syntax to distinguish between regular expressions for field keys and regular expressions for tag keys in the SELECT clause. The syntax /<regular_expression>/::[field | tag] is not supported.

SELECT MAX(/_level/) FROM "h2o_feet" LIMIT 1

Output:

This query uses the InfluxQL MAX() selector function to find the greatest field value out of all field keys that match the regular expression.

SELECT MEAN("degrees") FROM /temperature/

Output:

This query uses the InfluxQL MEAN() function to calculate the average degrees for every measurement in the [NOAA sample data] that contains the word temperature.

SELECT MEAN(water_level) FROM "h2o_feet" WHERE "location" =~ /[m]/ AND "water_level" > 3

Output:

This query uses the InfluxQL MEAN() function to calculate the average water_level where the tag value of location includes an m and water_level is greater than three.

SELECT * FROM "h2o_feet" WHERE "location" !~ /./
>

The query selects all data from the h2o_feet measurement where the location tag has no value. Every data point in the NOAA water sample data has a tag value for location. It’s possible to perform this same query without a regular expression. See the Frequently Asked Questions document for more information.

SELECT MEAN("water_level") FROM "h2o_feet" WHERE "location" =~ /./

Output:

This query uses the InfluxQL MEAN() function to calculate the average water_level across all data with a tag value for location.

SELECT MEAN("water_level") FROM "h2o_feet" WHERE "location" = 'santa_monica' AND "level description" =~ /between/

Output:

This query uses the InfluxQL MEAN() function to calculate the average water_level for all data where the field value of level description includes the word between.

SELECT FIRST("index") FROM "h2o_quality" GROUP BY /l/

Output:

This query uses the InfluxQL FIRST() function

to select the first value of index for every tag that includes the letter l in its tag key.