Estas son las notas para PDO:
Cita: How to use mssql pdo on PHP 5.3 on IIS 7 (Windows Server 2008)
1. Installation of MSSQL driver for PHP:
Download Microsoft Drivers for PHP for SQL Server Microsoft Drivers for PHP for SQL Server - SQLSRV20.EXE -
http://www.microsoft.com/downloads/en/details.aspx
?FamilyID=80e44913-24b4-4113-8807-caae6cf2ca05)
Copy php_sqlsrv_53_ts_vc9.dll and php_pdo_sqlsrv_53_ts_vc9.dll to php extension directory
2. configure php.ini to work with MSSQL PDO
extension=php_sqlsrv_53_ts_vc9.dll
extension=php_pdo_sqlsrv_53_ts_vc9.dll
3. configure configuration
'connectionString' => 'sqlsrv:server=hostname_or_ip;Database=database_na me;',
Saludos.