How to get average in gauge from multiple values?


I have selectable variable ‘item’ in dashboard which corresponds item tag in measurement and want to show some average value in gauge.

I am running query:

select sum(“value1”) / sum(“value2”) from mymeasurement WHERE $timeFilter GROUP BY item

Whenever I have only 1 item tag in measurement, query runs ok, but when there are two or more, I am getting ‘Only queries that return single series/table is supported’

Can someone help me to find proper query for multiple items? Thanks!