non-blocking-io.js

// Require nodes http module
var http = require('http');

// Require a third party mysql module (use "npm install mysql" to install it)
var mysql = require('mysql');

// Create a connection pool
var pool = mysql.createPool({
    host: 'localhost',
    user: 'username',
    password: 'password',
    database: 'test'
});

// Create an instance of http server that listens on localhosts port 3000
var server = http.createServer().listen(3000, '127.0.0.1', function () {
    var port = server.address().port;
    console.log('http server is listening on port %s', port);
});

// Register a callback to the 'request' event
server.on('request', function (request, response) {


    // Request a connection from the pool and define a callback
    pool.getConnection(function (error, connection) {

        if (error) {
            response.writeHead(500, {'Content-Type': 'text/html'});
            response.write("Error connecting to database: " + JSON.stringify(error));
            response.end();
            return;
        }


        // We got a connection object and call the query on it and define a callback
        connection.query('SELECT * FROM Person', function (error, rows) {

            if (error) {
                response.writeHead(500, {'Content-Type': 'text/html'});
                response.write("Error when selecting from database: " + JSON.stringify(error));
                response.end();
                return;
            }

            // Free the connection
            connection.release();

            response.writeHead(200, {'Content-Type': 'text/html'});
            // Send result as string to the browser
            response.write(JSON.stringify(rows));
            response.end();
        });
    });
});


// Define some error handler
var onError = function (error) {
    console.log('onError: ');
    console.log(error);
    process.exit(1);
};

var onUncaughtException = function (ex) {
    console.log('onUncaughtException: ');
    console.log(ex);
    console.log(ex.stack);
    process.exit(1);
};

// HTTP Server level error like EADDRINUSE
server.on('error', onError);

// Uncaught exceptions
process.on('uncaughtException', onUncaughtException);