That is my biggest pet peeve EVER! Opening and closing the db connection! I’ve seen it for more than 24 years now! How idiotic that this persists into 2018! (pun intended).
Plus going OOP versus Procedural is all dependent on how BIG and involved the application is. Heck, even on a monster sized app, if the file structure is done right, procedural is the way to go.
But once you get to a big application, with multiple programmers working on different sections in the same environment you usually don’t have a choice but doing oop.