First, let me say it's my first time using node-red and reading this forum has helped more than you can imagine. I knew nothing about node-red and now I'm about to finish my IoT project.
I'm managing hand sanitizer dispensers (my mqtt broker sends me a topic with the number of pumps, and then I send that data to mysql and calculate how much hand sanitizer is left).
So I have this table (view) on mysql that shows the last update from each device, with his full capacity and whats left.
I need to translate this information on gauge graphs showing how much is left in each device. But I can't seem to find out how to do it.
I only have this
on my function I wrote
msg.topic="SELECT full_capacity, (full_capacity-(nr_pumps*3)) FROM left_capacity;" return msg;
but I know this is wrong, because node-red has no ideia which device to pull information, etc.
Any help would be much appreciated, thanks in advance.