nodejs中如何连接mysql，下面给出一个小Demo.

第一步安装mysql模块
npm install mysql

第二步导入mysql模块
var mysql = require('mysql');

第三步连接mysql数据库
var connection = mysql.createConnection({
    host:'localhost',
    user:'root',
    password:'',
    database:'yudi'
});

connection.connect();
第四步执行一条查询语句
var sql = "select * from person where name='"+username+"'";
connection.query(sql,function(err,rows,fields){
     if(err)
         console.log(err);
     else{
        console.log(rows);
     }
//记得关闭连接
　　 connection.end();
});
err:是错误信息
rows：查询的信息
fields:返回所有信息
下面是小Demo

var mysql = require('mysql');

var connection = mysql.createConnection({

    host:'localhost',

    user:'root',

    password:'',

    database:'yudi'

});

connection.connect();

var username = 'stu2';

var sql = "select * from person where name='"+username+"'";

connection.query(sql,function(err,rows,fields){

    if(err)

        console.log(err);

    else{

        console.log(rows);

    }

        connection.end();//记得关闭连接

});