Change mouse pointer


I made my first ruby/ROR web site. Now, I would like to improve it.
In a page, I have a “link_to_remote” object. When I click it, a method
of my controller is called. This method executes a DB query and the
result is set on the web page.
The thing that I would like to do is to change the mouse pointer when I
click on the link_to_remote object so the user see that the operation is
After the query ended, I want to put back the mouse pointer.

What is the best approach to do that?