How to show a combined graph (temperature vs gas usage)?

Dear openhab colleagues,
To heat my house we have a gas driven central heating system. To see whether some adaptions I make, I am trying to show a combined graph in which on the x-axis there is the temperature and on the y-axis the gas-usage.
I have some scripts to join the average temperature on a given day with the gas-usage for that same day in a sql database. This is working fine.
Now I want to display that but I am not succeeding. Tried grafana but that is needing a time based series. There are some guides but they use only a table to present it while I think a graph would be nicer.
Does anyone have some suggestions? Tried already searching the forum but couldn’t find anything in this direction.

Thanks already for helping / pointing out. Best regards.