Node.js with SQL: ERR_EMPTY_QUERY - mysql

Question

I am trying to create a service with MySQL as database. I have my query stored in the database and am calling it in the node.js service. It is a two step process as the first query will give the query to be the run as the result to next connection. However my first part is working fine but when the connection moves to second part it gives ERR_EMPTY_QUERY.
Here is my code. The error is at the second part connection.query(dbresult, function (err, done)).
var async = require('async');
module.exports.getChart = function (chartcode,filter,callback){
var fuelweekquery= "SELECT * FROM t_chart_val where CHART_CODE=?"
if (null == filter || "week"==(filter)){
result= fuelweekquery;
}
async.parallel([
function (callback) {
//if(null==filter || "day"==(filter))
pool.getConnection(function (err, connection) {
connection.query(result,[chartcode], function (err, done) {
if (err) {
connection.release();
}
for (var i in done) {
dbresult = done[i].CHART_ATTR_VAL;
}
callback(err, done);
}
);
});
},
function (callback) {
//if(null==filter || "day"==(filter))
pool.getConnection(function (err, connection) {
connection.query(dbresult, function (err, done) {
if (err) {
connection.release();
}
//connection.release();
console.log(done);
callback(err, done);
}
);
});
},
], function (err, results) {
if (err) console.log(err);
//console.log('queries finished', results);
callback(null, results);
});
}

Answer 1

According to caolan async documentation (Source),
Run the tasks collection of functions in parallel, without waiting until the previous function has completed. If any of the functions pass an error to its callback, the main callback is immediately called with the value of the error. Once the tasks have completed, the results are passed to the final callback as an array.
Therefore it does not wait for the first in the array to complete before executing the second, for this I would recommend you use async waterfall
async.waterfall([
function(callback) {
//Your DB operation
callback(null, dbresult );
},
function(dbresult, callback) {
// use dbresult for your second operation
callback(null, 'done');
}
], function (err, result) {
// result now equals 'done'
});