Let Node.js and PHP use the same database(mysql)?

install mysql module for nodejs.

npm install mysql

using his module you can use the mysql database

var mysql = require('mysql');
var conn = mysql.createConnection(
    {
      host     : 'localhost',
      user     : '.....',
      password : '......',
       database : '.......'
    }
);
conn.connect();

var queryString = 'SELECT * FROM .............';
conn.query(queryString, function(err, rows, fields) {
            if (err) { 
                 console.log(err);
            } else {
                        console.log(rows);
                    }
});

There's a module for nodejs that allows you to connect to MySQL. It is pretty easy to use:

var mysql      = require('mysql');

var conn = mysql.createConnection({
     host     : 'localhost',
     user     : 'root',
     password : ''
});

conn.connect(function(err) {});