This is a small article about how to use node.js as web server to display the results of a query to a MySQL database engine.
The first thing to do is to check is that we have installed the mysql module to run it the following:

lucaMac:BLOG\_POSTs pepo$ node \> var Client = require('mysql').Client Error: Cannot find module 'mysql' at Function.\_resolveFilename (module.js:332:11) at Function.\_load (module.js:279:25) at Module.require (module.js:354:17) at require (module.js:370:17) at repl:1:14 at REPLServer.eval (repl.js:80:21) at repl.js:190:20 at REPLServer.eval (repl.js:87:5) at Interface. (repl.js:182:12) at Interface.emit (events.js:67:17) \> If fails, proceed to install the module via npm:

npm install mysql

The first thing we do is create the object for the query:

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var Client = require('mysql').Client,  
client = new Client();  
client.user = 'user';  
client.password = 'password';  
client.host='127.0.0.1';  
client.port='3306';  
client.database='database\_name'  
client.connect();

then create the web server

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var http = require('http');  
http.createServer(function (req, res) {  
res.writeHead(200, {'Content-Type': 'text/plain'});

And within this we perform the query, and associate to its callback function

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client.query(  
"select \* from table where campo1 > 1 limit 10;",      
function select(err, results, fields) {  
if (err) {  
console.log("Error: " + err.message);  
throw err;  
}

print data to the console and the web response

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console.log("Number of rows: "+results.length);  
console.log(results);  
  
  
for (var i in results){  
  
var result = results\[i\];  
res.write(result.campo1+"\\n");  
}  
  
res.end();  
});

We finished the code, setting up a port for listening

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}).listen(1337, "0.0.0.0");  
console.log('Server running ');

The finished script is like this:

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var Client = require('mysql').Client,  
client = new Client();  
client.user = 'user';  
client.password = 'password';  
client.host='127.0.0.1';  
client.port='3306';  
client.database='DB'  
client.connect();  
  
  
var http = require('http');  
http.createServer(function (req, res) {  
res.writeHead(200, {'Content-Type': 'text/plain'});  
  
  
client.query(  
"select \* from table where campo1 > 1 limit 10;",      
function select(err, results, fields) {  
if (err) {  
console.log("Error: " + err.message);  
throw err;  
}  
console.log("Number of rows: "+results.length);  
console.log(results);  
res.write(results);  
  
for (var i in results){  
  
var result = results\[i\];  
res.write(result.campo1+"\\n");  
}  
res.end();  
});  
  
}).listen(1337, "0.0.0.0");  
console.log('Server running ');

If you want to download this is the link to the   gist

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