The access control system was made with the Arduino and Arduino Ethernet Shield.
Author explains about his project.
The video shows how to use an arduino to make an access control system reading the id on the badge (card or key) sending it back to a server for validation/access control/whatever you want.
When RFID card is near the RFID Reader, it beeps and then the RFID number is sent to the server through the Arduino Ethernet Shield.
The demo shows the author used the PostgreSQL server.
PostgreSQL(http://www.postgresql.org) is the open source RDBMS that is popular in North America and Japan.
Refer to this link for Video.