hi..
my name is risya, 
my final year project is about price indicator trolley
i use barcode scanner,usb host shield and arduino, i just put coding detailed of the product in arduino coding.
i need to do real time database so user or client can edit online detailed of the product through online.
do you have any idea ??
There is stuff , Google will find you on this , it's a learning exercise I guess ...
If you have a remote mySQL database (for example), you create html/php pages which query or update the database.
From your network connected Arduino, you issue http GET (or PUT) statements which use these html/php pages to access and manipulate the database.
There are, of course, other ways of achieving the same thing.