Book Image

Learning PHP Data Objects

By : Dennis Popel
Book Image

Learning PHP Data Objects

By: Dennis Popel

Overview of this book

PDO is lighter, faster, and more powerful than existing PHP data abstraction interfaces. PDO is a common interface to different databases that must be used with a database-specific PDO driver to access a particular database server: the PDO extension does not provide a database abstraction by itself; it doesn't rewrite SQL, emulate missing database features, or perform any database functions using by itself. It performs the same role as other classic database abstraction layers such as ODBC and JDBC: it's a query abstraction layer that abstracts the mechanism for accessing a database and manipulating the returned records; each database driver that implements the PDO interface can also expose database-specific features as regular extension functions. ¬ PDO ships with PHP 5.1, and is available as an extension for PHP 5.0; it requires the new object-oriented features of PHP 5, and cannot run with earlier versions of PHP.This book will teach you how to use the PDO, including its advanced features. Readers need to be aware of the basics of data abstraction and should be familiar with PHP.
Table of Contents (13 chapters)

Connection Strings

Connection strings, or data source names (abbreviated DSN) as they are called in the PDO documentation, are PHP strings that carry such information as the name of the database management system and of the database itself, as well as other connection parameters.

Their advantage over using traditional methods of creating database connection is that you don't have to modify your code if you change the database management system. A connection string can be defined in a configuration file and that file gets processed by your application. Should your database (data source) change, you just edit that configuration file and the rest of your code is kept intact.

The connection strings used in PDO differ due to the existence of different database management systems. However, they always have a common prefix, which denotes the underlying database driver. Remember the MySQL, SQLite, and PostgreSQL examples in the Chapter 1. The three connection strings looked like the following: