The dbx module is a database abstraction layer (db 'X', where 'X' is a supported database). The dbx functions allow you to access all supported databases using a single calling convention. The dbx-functions themselves do not interface directly to the databases, but interface to the modules that are used to support these databases.
To be able to use a database with the dbx-module, the module must be either linked or loaded into PHP, and the database module must be supported by the dbx-module. Currently, following databases are supported, but others will follow (soon, I hope :-):
FrontBase (available from PHP 4.1.0).
Sybase-CT (CVS only).
Documentation for adding additional database support to dbx can be found at http://www.guidance.nl/php/dbx/doc/.
In order to have these functions available, you must compile PHP with dbx support by using the --enable-dbx option and all options for the databases that will be used, e.g. for MySQL you must also specify --with-mysql=[DIR]. To get other supported databases to work with the dbx-module refer to their specific documentation.
This extension does not define any configuration directives.
These constants are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.