Create database.js file ( config/database.js)

    const {
        createPool
    } = require("mysql");
    
    const pool2 = createPool({
        host: process.env.MYSQL_HOST,
        port: process.env.MYSQL_PORT,
        user: process.env.MYSQL_USER,
        password: process.env.MYSQL_PASSWORD,
        database: process.env.MYSQL_DATABASE,
        connectionLimit: 10
    });

    const pool = createPool({
        host: "localhost",
        port: 3306,
        user: "root",
        password: "root",
        database: "training_db",
        connectionLimit: 1
    });
    
    
    module.exports = pool;