DBM-style Database Abstraction
PHP offers support for many databases. Open source relational databases are well represented, as are many commercial products. If native support for a database doesn't exist, it's likely you may use ODBC with an appropriate driver. Chapter 17, "Database Integration," discusses strategies for using databases with PHP-powered sites.
Most of the functions in this section rely on an extension module. These may be loaded either in the php.ini file or the dl function, but most likely are compiled into PHP. Typically Windows requires use of the first method and other operating systems require the second. ...