Okay, then I change the focus of the project.
I will communicate by mqtt arduino and OH, and also by the persistencies, I will connect OH with MySQL, however it is not clear to me the 3 levels that Rlkoshak speaks,
my idea is to be able to see the data table saved by OH in it, but you They say they can not read constantly, only when they start.
How do I see the data stored in MySQL in OH?
I forgot something, I had the idea that openhab will be modified from the BD since I also plan to make a separate android application just to modify a parameter (item), I do not want to use the application that brings OH2 because I do not want to have access to all the items.
For that reason I had the idea that OH2 would be modified from BD and that the arduino and android app would modify it.
Do you have any idea about this?
Thank you very much for reply, they have helped me a lot