how to use sql in node.js code example

Example 1: how to manage a db connection in javascript

//put these lines in a seperate file
const mysql = require('mysql2');

const connection = mysql.createPool({
    host: "localhost",
    user: "",
    password: "",
    database: ""
    // here you can set connection limits and so on
});

module.exports = connection;

//put these on destination page
const connection = require('../util/connection');

async function getAll() {
    const sql = "SELECT * FROM tableName";
    const [rows] = await connection.promise().query(sql);
    return rows;
} 
exports.getAll = getAll;

Example 2: js read mysql database

// Use https://github.com/JackChilds/jsmysqldb

// Then once it's setup you can just do this:

// Config that will be sent to server
const config = {
  "table" : "customers",
  "limit" : "50",
  "offset" : "0"
};

// Use the _POST_REQUEST function to send data to the server and get a response
_POST_REQUEST("link-to-server/database.php", 'config=' + JSON.stringify(config), (response) => {
  // Convert the response into an array of rows:
  var data = JSON.parse(response);
  // Now do what you want with data
  // data[row index][column name]
});