In addition to normal ODBC support, the Unified ODBC functions in PHP allow you to access several databases that have borrowed the semantics of the ODBC API to implement their own API. Instead of maintaining multiple database drivers that were all nearly identical, these drivers have been unified into a single set of ODBC functions.
Note: There is no ODBC involved when connecting to the above databases. The functions that you use to speak natively to them just happen to share the same names and syntax as the ODBC functions. The exception to this is iODBC. Building PHP with iODBC support enables you to use any ODBC-compliant drivers with your PHP applications. iODBC is maintained by OpenLink Software. More information on iODBC, as well as a HOWTO, is available at www.iodbc.org.
To access any of the supported databases you need to have the required libraries installed.
Please see the Database installation options chapter for more information about configuring PHP with these databases.
The behaviour of these functions is affected by settings in php.ini.
Table 1. Unified ODBC Configuration Options
Note: Entries marked with * are not implemented yet.
Here is a short explanation of the configuration directives.
Whether to allow persistent ODBC connections.
Check that a connection is still valid before reuse.
The maximum number of persistent ODBC connections per process.
The maximum number of ODBC connections per process, including persistent connections.
Handling of LONG fields. Specifies the number of bytes returned to variables.
Handling of binary data.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.