Note: This manual is provided for your convenience only - this is not the official source and may not be 100% up to date.
XCIII. Microsoft SQL Server and Sybase Functions (PDO_DBLIB)
PDO_DBLIB is a driver that implements the PHP Data Objects (PDO) interface to enable access from PHP to Microsoft SQL Server and Sybase databases through the FreeTDS libary.
On Windows, you should use the PDO_ODBC driver to connect to Microsoft SQL Server and Sybase databases, as the native Windows DB-LIB is ancient, thread un-safe and no longer supported by Microsoft.