Hello, I have managed to store data in MySQL database using python (with mysqldb). It basically reads an RFID card and gets the user's choice using pushbuttons. RFID card's UID number and button name is stored in the database.
Now, the Arduino should check the database if the card has been used before. I don't have an Ethernet shield. Is it possible without a shield ?
I have found similar posts but all of them are using ethernet (or other) shields.
In that case indeed Serial is your solution.
Have some application running on your computer that connects to the USB port, then reads the commands from the Arduino, queries the database, and returns the result.