Multiple sql queries in nodejs

Question

I am new in nodejs.I am developing a demo app using nodeJs.I have problem while run multiple queries.My Code is like:

exports.dashboard = function(req, res){

 req.getConnection(function(err,connection){

 var id = req.session.userId;
  var queryData =  "SELECT node_questions.question_name,node_questions.description FROM node_questions LEFT JOIN node_user ON node_questions.user_id=node_user.id";
        var query = connection.query(queryData,'SELECT * FROM node_user Where id = ?',[id],function(err,rows)
        {
                console.log(rows);
               res.render('dashboard',{page_title:"Dashboard",session:req.session.userId,email:req.session.email,data:rows});
         });
    });  
};

Database connection is:

 app.use(
        connection(mysql,{
            host: 'localhost',
            user: 'root',
            password : 'password',
            port : 3306, //port mysql
            database:'nodeDemo',
            multipleStatements:true

        },'pool') //or single

    );

Answer 1

why not use Promise?

let Promise = require('bluebird'),
    begin = []

begin.push(promise1(a,b))
begin.push(promise2(c.d))

return Promise.all(begin)
    .spread(function (resultFromQuery1, resultFromQuery2) {
        // do something with the result here
    })

Answer 2

You are mixing things together. For example what would you expect your rows to be ? Should it be the result-set of the first or the second query ? A good way to handle this would be to use async module (ensure you install it via npm in your package.json first).

var async = require('async');
var mysql      = require('mysql');

client = mysql.createConnection({
    user: 'root',
    password : 'password',
    port : 3306, //port mysql
    database:'nodeDemo',
    multipleStatements:true
});

var id = req.session.userId;

async.parallel([
    function(callback) {
        var queryData = '' +
            ' SELECT node_questions.question_name,node_questions.description' +
            ' FROM node_questions' +
            ' LEFT JOIN node_user' +
            ' ON node_questions.user_id=node_user.id';
        client.query(queryData, function (err, rows1) {
            if (err) {
                return callback(err);
            }
            return callback(null, rows1);
        });
    },
    function(callback) {
        client.query('SELECT * FROM node_user Where id = ?', id, function (err, rows2) {
            if (err) {
                return callback(err);
            }
            return callback(null, rows2);
        });
    }
], function(error, callbackResults) {
    if (error) {
        //handle error
        console.log(error);
    } else {
        console.log(callbackResults[0]); // rows1
        console.log(callbackResults[1]); // rows2
        // use this data to send back to client etc.
    }
});