MySQL Cookbook, 2nd Edition

Using MySQL-Based Storage with the PHP Session Manager

Problem

You want to use session storage for PHP scripts.

Solution

PHP includes session management. By default, it uses temporary files for backing store, but you can configure it to use MySQL instead.

Discussion

This section shows how to use the PHP native session manager and how to extend it by implementing a storage module that saves session data in MySQL. If your PHP configuration has the track_vars configuration variable enabled, session variables are available as elements of the $HTTP_SESSION_VARS global array or the $_SESSION superglobal array. track_vars is always enabled as of PHP 4.0.3, so I’ll assume that this is true for your PHP installation. If the register_globals configuration variable is enabled as well, session variables also exist in your script as global variables of the same names. However, this is less secure, so this variable is assumed not to be enabled here. (Collecting Web Input discusses PHP’s global and superglobal arrays and the security implications of register_globals.)

The PHP session management interface

PHP’s session management capabilities are based on a small set of functions, all of which are documented in the PHP manual. The following list describes those likely to be most useful for day-to-day session programming:

session_start ()

Opens a session and extracts any variables previously stored in it, making them available in the script’s global namespace. For example, a session variable named