Use Yii Models in custom PHP code

gistfile1.php

<?php
/**** Initialize Yii */
require_once($_SERVER['DOCUMENT_ROOT'].'/path/to/yii/framework/yii.php');
Yii::createWebApplication($_SERVER['DOCUMENT_ROOT'] . '/path/to/config/main.php');

// ...


$product = Product::model()->findByPk(3);