Display the tag if value is NULL


I have a tag in a measurement. My influxdb is displaying data for every 2 min. For one of the tag there is no value from past 30 minutes. So it is not displaying any output in fluxdb. I want to display that tag name even if the value is NULL.

I think the only way to do that is to use the FILL function to replace nulls with another value.
note that if there is no data for the time interval, nothing will be displayed even if FILL is used.