Javascript 错误：连接丢失：服务器已关闭连接。mysql节点

我在谷歌看到了很多解决这个问题的方法，但我无法应用它们。API运行良好，但一段时间后出现此错误

index.js

const express = require('express');
const app = express();
const router = express.Router();
const path = require('path');
const habalka = require('./routes/habalka')(router);

const port = process.env.PORT || 3000;

app.use('/api/habalka', habalka);

app.get('/', (req, res) => {
    res.sendFile(path.join(__dirname + '/index.html'));
});

app.listen(port, () => console.log(`Example app listening on port ${port}!`));

db.js

habalka.js

 const connect = require('../db');

    module.exports = (router) => {

    router.get('/get', (req, res) => {
        let sql = 'SELECT * FROM test';
        connect.query(sql, (err, results) => {
            if (err) throw err;

            res.json(results);
        });
    });

    return router;
};

---

我建议使用Sequelize ORM。它将编写原始SQL抽象出来，而且更安全

 const connect = require('../db');

    module.exports = (router) => {

    router.get('/get', (req, res) => {
        let sql = 'SELECT * FROM test';
        connect.query(sql, (err, results) => {
            if (err) throw err;

            res.json(results);
        });
    });

    return router;
};