On PHPBuilder.com today, there's a new tutorial focusing on the development of PHP applications that can be run on different database environments without many changes to the actual application.

There are several options available to interact with multiple database engines with PHP, such as Pear DB and MDB2. However, there may instances where you will be required to develop your own custom database interface that connects to many different database engines using a single unified syntax. This article will address the development of a class that will do exactly that. In addition, we will include the ability to replicate data among several databases in real time.

They create their own abstraction layer that has the ability to make the connection, replicate data between connections, handle some errors and work with database configuration data. The tutorial shows you how to use the script for three different database types - MySQL, Oracle, and MS SQL.