If you want to access MS SQL Server in your PHP script, you need to make sure that:

1. MSSQL API module (extension) is installed and turned on in your PHP engine. If you installed the Windows binary version of PHP 5.2.3, MSSQL API module is included but not turned yet. See the next tutorial on turning on MSSQL API module.

If you are getting errors like: "Fatal error: Call to undefined function mssql_connect()", you know that MSSQL API module is not turned on correctly. See the next tutorial on turning on the MSSQL API module.

2. MS SQL Client Tools to be installed on the system where PHP is installed. The PHP manual also suggested an alternative, which is to get a copy of the SQL Server Client Libarary DLL, ntwdblib.dll. Again Windows binary version of PHP 5.2.3 contains a copy of ntwdblib.dll.

If you are getting errors like: "Unable to load dynamic library './extphp_mssql.dll' - The specified module could not be found", you know that the DLL, ntwdblib.dll, is not installed correctly. See the next tutorial on installing ntwdblib.dll.