Update screen via ajax with DB data

[eluser]MarceloTM[/eluser]
Hello everyone, I'm trying to develop a 'pizza delivery' software, but the problem is that I need to update some field or flash some alert on the admin screen when someone makes a request from anywhere on the galaxy.
How can I make the DB send the data to the right place when someone makes a request? I'm using mySQL and jQuery for the ajax and I don't know if has anything to do with triggers, since I never used them...

Please, can anyone help?