[SOLVED] Addition of 2 last() values

Addition of 2 last() values

I'm trying to add 2 values in a single query, retrieved using the last() operator.

In our setup, these two values can be selected by:

SELECT last("value_number") FROM "states_history" WHERE ("state_id" = '263083')

and

SELECT last("value_number") FROM "states_history" WHERE ("state_id" = '263084').

So a quite simple setup, however, adding these two values within a single query seems impossible. The closest I got was using sub-queries:

SELECT (pkw1 + pkw2) AS pkw FROM 
    (SELECT last("value_number") AS pkw1 FROM "states_history" WHERE ("state_id" = '2630833') GROUP BY time(1d)), 
    (SELECT last("value_number") AS pkw2 FROM "states_history" WHERE ("state_id" = '2630834') GROUP BY time(1d))

I had to add the GROUP BY, otherwise Influx wouldn't accept the sub-querie. However, this still didn't lead to a usable result.

Could someone point me in the right direction? The addition of 2 scalar values (not time series) shouldn't be hard after all?

I googled for over an hour
read the influxql docs on additions and subtractions
tried several combinations of queries, most not accepted by the influx

Solution

InfluxDB does not support joining subqueries directly. you can use a combination of JOIN and GROUP BY to achieve this. This is the simplified version . I think this will work.

SELECT sum("value_number") AS pkw FROM (
    SELECT last("value_number") AS "value_number" FROM "states_history"
    WHERE ("state_id" = '263083') OR ("state_id" = '263084')
    GROUP BY "state_id"
)