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, the following databases are supported, but others will follow:
FrontBase (available from PHP 4.1.0).
Sybase-CT (available from PHP 4.2.0).
Oracle (oci8) (available from PHP 4.3.0).
SQLite (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.
这些函数的行为受到全局配置文件 php.ini 的影响。
For further details and definition of the PHP_INI_* constants see ini_set().
注: This ini-option is available available from PHP 4.3.0.
以下是该配置选项的简要解释。
Columns names can be returned "unchanged" or converted to "uppercase" or "lowercase". This directive can be overridden with a flag to dbx_query().
There are two resource types used in the dbx module. The first one is the link-object for a database connection, the second a result-object which holds the result of a query.
由于这些常量是由该扩展模块定义的，因此只有在该扩展模块被编译到 PHP 中，或者在运行时被动态加载后，这些常量才有效。