I work primarly with PHP & MySQL, but I have a potential client with a MS SQL and ASP setup. Due to some complicated reasons and offline software integration, they need
Also you can use sqlsrv if you are using PHP5.3+
Form microsoft
Microsoft Drivers for PHP for SQL Server, version 3.1 requires PHP 5.4.32, or PHP 5.5.16, or later. Microsoft Drivers for PHP for SQL Server, version 3.0 requires PHP 5.3.0 or later. If possible, use PHP 5.3.6, or later.
Microsoft download page : microsoft sqlsrv download
Microsoft SQL Server Driver for PHP Manual : php sqlsrv manual