Connessione MSSQL tramite PHP

Ti consiglio di scarica i binari del server sql da Windows e utilizzare PDO.

try { 
        //In some occasions you only need to define IP/Hostname and you can forgo the \SQLEXPRESS part
        $db = new PDO( "sqlsrv:Server=HOSTNAME\SQLEXPRESS;Database=DATABASENAME","USERNAME","PASSWORD");
       $db->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
       // set this to your primary database
      $db->query("USE DATABASENAME");
    }

    catch( PDOException $e ) { 

       die( "Error connecting to SQL Server".$e ); 
    }