Introduction

According to Wikipedia, “the active record pattern is a design pattern frequently found in software that stores its data in relational databases. Active record is an approach to accessing data in a database.” And admittedly, this definition accurately outlines the functionality of this pattern, even though it sounds hard to grasp at first. 

In many cases (though not all), implementing the active record pattern for a given web application requires the creation of a class instance that will be tied to each row of a database table. Based upon this schema, this instance will be used basically to select, update, insert and delete database records (also known as CRUD operations), without having to explicitly write any SQL statements.

Obviously, one of the major advantages in using the active record pattern when developing a database-driven application is the one described above: SQL abstraction. Instead of having to code raw, hard-to-maintain selects, inserts, updates, and deletion operations at different points of the application to access data stored in a database, the methods of a data mapper object are used to encapsulate all the SQL code necessary to perform all these tasks “behind the scenes.”

Utilizing data mapping objects isn’t the only way to apply the active record pattern, since it’s also feasible to achieve similar results by means of a database abstraction class that implements a bunch of methods that permit interaction with database tables without having to code SQL clauses from scratch.

Even though this approach isn’t as popular as using data mappers, it has been adopted progressively by many programmers nowadays. In the case of PHP, popular frameworks like CakePHP and Code Igniter use this approach for implementing active record classes in a pretty successful way.

Thus, in this series of articles, I’ll be explaining how to develop an active record class in PHP, which will allow you to perform selects, updates, inserts, and deletion operations against a selected MySQL database table in a simple fashion. As is typical of my approach, I'll use numerous code samples to make my points clear. 

I’ll start with a class written in PHP 4 that will implement a few simple methods, and then, when you understand how it works, I’ll add more complexity and functionality.

Are you ready to learn how to apply the active record pattern with PHP? Then don’t waste more time in preliminaries; start reading now!