node.js Development Guide – Node.js connects to MySQL and performs database operations_node.js

Node.js is a JavaScript toolkit for writing high-performance web servers

Usually in NodeJS development, we often involve operating databases, especially MySQL. As the most widely used open source database, it has become our first choice. This article will introduce how to operate MySQL database through NodeJS. Install the MySQL module into NodeJS. If we need to make NodeJS support MySQL, we need to add the MySQL module to the system support library

If you want to quickly learn about Node.js, Zansheng recommends taking a look at node.js_guide.pdf — node.js Development Guide: If you want a high-definition electronic version, please send a message

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Node.js
Let’s briefly introduce the operation of node.js
Install node-mysql
C code

$ npm install mysql 

Create test table
//Database name NodeSample
C code

CREATE TABLE `NodeSample`.`MyTable` ( 
`id` INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY , 
`firstname` VARCHAR( 20 ) NOT NULL , 
`lastname` VARCHAR( 20 ) NOT NULL , 
`message` TEXT NOT NULL 
) ENGINE = MYISAM ; 

Connect to database
Js code

var sys = require('sys'); 
 
var Client = require('mysql').Client; 
var client = new Client(); 
 
client.user = 'someuser'; 
client.password = 'password'; 
 
client.connect(function(error, results) { 
if(error) { 
console.log('Connection Error: ' + error.message); 
return; 
} 
console.log('Connected to MySQL'); 
}); 

Open database
Js code

ClientConnectionReady = function(client) 
{ 
client.query('USE NodeSample', function(error, results) { 
if(error) { 
console.log('ClientConnectionReady Error: ' + error.message); 
client.end(); 
return; 
} 
}); 
}; 

Complete database operation procedures
Js code

var sys = require('sys'); 
 
var Client = require('mysql').Client; 
var client = new Client(); 
 
client.user = 'someuser'; 
client.password = 'password'; 
 
console.log('Connecting to MySQL...'); 
 
client.connect(function(error, results) { 
if(error) { 
console.log('Connection Error: ' + error.message); 
return; 
} 
console.log('Connected to MySQL'); 
ClientConnectionReady(client); 
}); 
 
ClientConnectionReady = function(client) 
{ 
client.query('USE NodeSample', function(error, results) { 
if(error) { 
console.log('ClientConnectionReady Error: ' + error.message); 
client.end(); 
return; 
} 
ClientReady(client); 
}); 
}; 
 
ClientReady = function(client) 
{ 
var values = ['Chad', 'Lung', 'Hello World']; 
client.query('INSERT INTO MyTable SET firstname = ?, lastname = ? , message = ?', values, 
function(error, results) { 
if(error) { 
console.log("ClientReady Error: " + error.message); 
client.end(); 
return; 
} 
console.log('Inserted: ' + results.affectedRows + ' row.'); 
console.log('Id inserted: ' + results.insertId); 
} 
); 
GetData(client); 
} 
 
GetData = function(client) 
{ 
client.query( 
'SELECT * FROM MyTable', 
function selectCb(error, results, fields) { 
if (error) { 
console.log('GetData Error: ' + error.message); 
client.end(); 
return; 
} 
// Uncomment these if you want lots of feedback 
//console.log('Results:'); 
//console.log(results); 
//console.log('Field metadata:'); 
//console.log(fields); 
//console.log(sys.inspect(results)); 
 
if(results.length > 0) 
{ 
var firstResult = results[0]; 
console.log('First Name: ' + firstResult['firstname']); 
console.log('Last Name: ' + firstResult['lastname']); 
console.log('Message: ' + firstResult['message']); 
} 
}); 
 
client.end(); 
console.log('Connection closed'); 
};