How do i upgrade osCommerce v2.2 to v2.3.1?

How do i upgrade osCommerce v2.2 to v2.3.1? Is there a upgrade script available for that? Do I have to upgrade it 开发者_高级运维to v2.3.0 before upgrading to v2.3.1?

Download and unzip the latest version of osCommerce v2.3.1. Inside the folder you will find an upgrade_guide.pdf - open it. On the very first page, it tells you how to go about upgrading.

On page 2 you'll see a reddish shaded box and it says the following:

This upgrade guide only provides the minimum required changes in the form of security updates and bug fixes. These changes will not upgrade your store to a complete v2.3 version. Please continue to use v2.2 add-ons and do not install v2.3 optimized add-ons as the may not function with your installation. If you wish to upgrade to a full v2.3 version, perform only (SQL) Database Changes and use the database with a new v2.3 installation.