The SQL Server 2005 Driver for PHP is a PHP 5 extension that provides data access to SQL Server 2005. The extension provides a procedural interface for accessing data in all versions (including Express) of SQL Server 2005. The SQL Server 2005 Driver for PHP API includes support for Windows Authentication, transactions, parameter binding, streaming, metadata access, and error handling.(MSDN)The driver is available for download on the MSDN download site. MSDN also has a sample application and thorough documentation.
Microsoft has also published the source code to the driver on CodePlex under the Microsoft Public License (Ms-PL). Developers can use the source code to create their own builds, but Microsoft will only support the signed version of the driver from the MSDN download site.
Microsoft SQL Server 2005 Driver for PHP requires the Microsoft SQL Server 2005 ODBC Driver, which is only available on Windows. There are no plans to create a similar driver for other operating systems.