this is from the official site
https://codex.wordpress.org/Writing_a_Plugin
the web has many posts on how to write plugins just google
“how to write a wordpress plugin”
aslo se the youtube
If you want to pay for a video lesson there are many just google
It is not needed to be OO.
In order to speak with db you need the wpdb
this is the official link
https://codex.wordpress.org/Class_Reference/wpdb
Just google and you will find a lot
In general wordpress it is not so difficult. Good luck
solved implement wordpress plugin with php code project [closed]