Pear DB
PEAR is a framework and distribution system for reusable PHP
components
Metabase Package of classes that provide DBMS
independent access and management of databases.
PHPLIB PHPLIB is an object-oriented application
development toolkit for PHP. It is primarily of benefit to Web
application developers, but contains classes which are useful to
other PHP develoepers as well.
MDB
PEAR MDB is a merge of the PEAR DB and Metabase php database
abstraction layers. It provides a common API for all support RDBMS.
The main difference to most other DB abstraction packages is that
MDB goes much further to ensure portability
DBX
The dbx module is a database abstraction layer (db 'X', where
'X' is a supported database) implemented in C