- Reference manual
There is a wealth on ODBC implementations that are completely or almost compatible to this interface. In addition, a number of databases are delivered with an ODBC compatible interface. This implies you get the portability benefits of ODBC without paying the configuration and performance price. Currently this interface is, according to the PHP documentation on this subject, provided by Adabas D, IBM DB2, Solid, and Sybase SQL Anywhere.
On MS-Windows, the ODBC interface is a standard package, linked