New Directives
New Object Model
Migrating from PHP 4 to PHP 5.0.x
PHP Manual

## Databases

There were some changes in PHP 5 regarding databases (MySQL and SQLite).

In PHP 5 the MySQL client libraries are not bundled, because of license problems and some others. For more information, read the FAQ entry.

There is also a new extension, MySQLi (Improved MySQL), which is designed to work with MySQL 4.1 and above.

Since PHP 5, the SQLite extension is built-in PHP. SQLite is an embeddable SQL database engine and is not a client library used to connect to a big database server (like MySQL or PostgreSQL). The SQLite library reads and writes directly to and from the database files on disk.

New Directives
New Object Model
Migrating from PHP 4 to PHP 5.0.x
PHP Manual