The SQLSRV extension allows you to access Microsoft SQL Server and SQL Azure databases. The 3.0 release of the driver supports SQL Server, beginning with SQL Server 2005, including SQL Server 2012 and SQL Server 2012 LocalDB. (For more information about LocalDB, see » PHP Driver for SQL Server Support for LocalDB and » SQL Server 2012 Express LocalDB.)
The SQLSRV extension is supported by Microsoft and available for download here: » http://msdn.microsoft.com/en-us/sqlserver/ff657782.aspx. SQL Server 2012 LocalDB can be downloaded here: » http://go.microsoft.com/fwlink/?LinkID=237665.