ReferenceError：找不到变量：需要。我该如何修复这个错误？

Question

我想从我的database.js 文件中导出一些函数，并将它们添加到同一文件夹中的另一个文件login.js 中。我还尝试在全局和函数中声明 require，这两种方法都不起作用。我正在使用node.js/express.js。

DATABASE.JS

let mysql = require('mysql');

const connection = mysql.createConnection({
    host: 'localhost',
    database: 'minigames',
    user: 'root',
    password: 'root'
});
    
function connected(){
    connection.connect((err) => {
        if(err) throw err;
        console.log("Connected...");
    })
}

function select(attribute){
    return new Promise((resolve, reject) => {
        let sql = `SELECT ${attribute} FROM player`;
        connection.query(sql, (err, result, field) => {
            if(err) reject(err);
            resolve(Object.values(JSON.parse(JSON.stringify(result))));
        })
    })
}

async function query(attribute) {
    return await select(attribute);
}


module.exports = {connection, connected, select, query};

LOGIN.JS

let userList = [];
function checkLogin(){
    const database = require('./database');
    let userListPromise = database.query('username, password');
    userListPromise
    .then()
    .then((values) =>{
        let i = 0;
        while(values[i] != null){
            userList.push(values[i]);
            i++;
        }
        console.log("list filled");
        console.log(userList);
    })
}
checkLogin();