How to get mean of partial available data in TICK script




This is how my data looks like in past 24 hours.

we can clearly see only couple of hours data is only available in the middle.

I am aiming to obtain average of what ever data available in past 24 hours. But my output isn’t giving any result.
Here is the TICK Script.

var Average = batch
    |query('''SELECT mean(voc) AS voc_0015BC0036000018 FROM "sensordata"."autogen"."voc"  WHERE eui = '0015BC0036000018' ''')

Step1 httpoutput:

Just wanted to get the average of the data. If 10 points are available, just get the average 10 points. I have tried using both fill(0) and fill(‘null’) .