Upgrading to PHP 5

Porting Code and Migrating Databases

Although the new mysqli extension has many benefits over the older extension, they come at a cost. Depending upon your code, porting to the new extension can be a surprisingly tiresome task. If you’ve used a database abstraction layer—such as PEAR DB, ADOdb, or MDB—this task is simplified considerably. Even though you’re only switching from one version of MySQL to another, the new extension is sufficiently different that quite a bit of work is necessary to make the switch.

However, you probably will want to use mysqli for your new projects, and that requires an upgrade to MySQL 4.1. Since an out-of-the-box MySQL 4.1 is incompatible with mysql, this presents a bit of a dilemma. You want the benefits of mysqli without worrying about legacy code.

Another option is just to make the switch to a database abstraction layer. This has some advantages and some disadvantages. The primary benefit is portability, but this comes at a cost of speed and features. For instance, you cannot bind output parameters with PEAR DB, nor does DB support all of the latest MySQLi options, such as mysqli_multi_query( ) and ssl_set( ).

This section presents a variety of options for handling the conversion process. Each one has various positive and negative attributes. Some require more hours of work; others are faster to implement, but at a cost of execution speed. None of these solutions are bad in and of themselves, but, given certain circumstances, some should be preferable ...