MVC+Express+MySQL+NodeJs

app_router.js

module.exports = function(app, connection){
  //Routing requests for /books
  app.use('/books', require('./books.router')(connection));
  //List any other potential routes below
}

books_controller.js

let BookModel =  require('../models/books_model');

//GET /books
async function getAllBooks(req, res, next) {
    try {
            await BookModel.query("select * from books", function (error,results, fields) {
             if (error) throw error;
             res.status(200).send(results);
             return;
            });
       
    } catch (error) {
        console.log(error);
        return next(error);        
    }
};

books_model.js

let 

books_router.js

let router = require('express').Router();
let controller = require('../controllers/books_controller');

//If a request comes like GET /books, this is the endpoint
router.route('/')
    .get(controller.getAllBooks);

module.exports = router;

index.js

const express = require('express');
const  app = express();
const mysql = require('mysql') //assuming you installed mysql( npm install mysql --save)


//Connect to the database
let connection = mysql.createConnection({  
      debug:true, 
      host:'localhost',
      user:'user',
      password:'password',
      database:'database'
  });
connection.connect(function(error){
    if(!!error){
      console.log(error);
    }else{
      console.log('Connected!:)');
    }
 });
//Load Routes
require('../routes/app_router')(app, connection); //this will be the first-level/app-level router responsible for loading specific endpoint routers

//Setup server
const PORT = 3000;
let server = app.listen(PORT, function(){
  console.log('Server listening on port ', PORT);
});

module.exports = server;