Question

我正在使用mysql数据库在节点js中开发一个项目。我想在index.j文件中执行查询。代码适用于两个连接但是当我添加第三个查询时，我不知道在结果[] []中使用什么数字。你能帮忙吗？谢谢。

这是index.js文件中的代码

router.get('/StudentPage', function (req, res, next) {
if (req.session && req.session.user) {
    pool.getConnection(function (err, connection) {

        async.parallel([
            function (callback) { connection.query('select * from students where Email = ' + connection.escape(req.session.user.Email), callback) },
            function (callback) { connection.query('select * from reservations where student_email = ' + connection.escape(req.session.user.Email), callback) },
            function (callback) { connection.query('select * from complaint where student_email = ' + connection.escape(req.session.user.Email), callback)}
        ], function (err, results) {
            if (!results[0][0]) {
                req.session.reset();
                res.redirect('/');
            } else {
                res.render('student', { title: 'Student Page', userinfo: results[0][0], reservations: results[1][0], complaints: results[2][0]});
            }
            connection.release();
        });
    });
} else {
    res.redirect('/');
}
});

Answer 1

尝试使用键值对象而不是async.parallel

的数组

// an example using an object instead of an array
async.parallel({
    one: function(callback){
        setTimeout(function(){
            callback(null, 1);
        }, 200);
    },
    two: function(callback){
        setTimeout(function(){
            callback(null, 2);
        }, 100);
    }
},
function(err, results) {
    // results is now equals to: {one: 1, two: 2}
});

例如：

router.get('/StudentPage', function (req, res, next) {
if (req.session && req.session.user) {
    pool.getConnection(function (err, connection) {

        async.parallel({
            students: function (callback) { 
                connection.query('select * from students where Email = ' + connection.escape(req.session.user.Email), callback) 
            },
            reservations: function (callback) { 
                connection.query('select * from reservations where student_email = ' + connection.escape(req.session.user.Email), callback) 
            },
            complaints: function (callback) { 
                connection.query('select * from complaint where student_email = ' + connection.escape(req.session.user.Email), callback)
            }
        }, function (err, results) {
            if (!results.students || !results.students[0]) {
                req.session.reset();
                res.redirect('/');
            } else {
                res.render('student', { 
                    title: 'Student Page', 
                    userinfo: results.students[0], 
                    reservations: results.reservations[0], 
                    complaints: results.complaints[0]
                });
            }
            connection.release();
        });
    });
} else {
    res.redirect('/');
}
});

节点js和mysql中的多个查询

1 个答案: