The easiest way that I connected to my access database, was using a simplified webserver and webpage. I used simple asp pages with no html codes to send and receive the data.(old school). So using a Ethernet card on the arduino, I would send data to the server as example http://192.168.0.79/arduino.asp?rfid=2345123 and the server would send a response as xml page. The arduino would parse the xml page and then run code based on it.
The nice part about using the webserver is that you can test it and the arduino separately.