//check this section code
function login (username, password, callback) {
    var check = false
    accountDB.serialize(function () {
        var sql = 'SELECT username,password FROM table01 WHERE username=?'
        accountDB.each(sql, [username], function(err, row) {
            console.log(':' + row.password)
            if (row.password === password) {
                check = true
                console.log('check true')
                callback(null, true);
            }
            callback('Username or password is wrong', null);
        })
    })
}