Using classes in PHP makes for a much more secure and reusable codebase. The below is an example of a MySQL connection class extended by a class that retrieves data from a MySQL database, sets its member variables to the resulting values, and returns it when necessary.
Note: This will only work in PHP5, any version lower than PHP 5.0 will throw fatal errors.
Also note: This is still a work in progress, as time constraints limit how much time I can spend on this per day, I will be adding more articles and/or expanding upon existing ones.