Merge last value from other column

I’m trying to merge last known value from one column into another.

So for every entry in data/count/value get the last known value from data/power/value and add it to the view. I’m using grafana here.

My query in the screenshot:
SELECT "Value" FROM "data/power/value", "data/count/value"

See the example bellow.

How how can I merge two columns in one.

Thank you in advance.