little help understanding how query to the server is made

[schmidty]

Hello Everyone,
I was hoping I could get a little help understanding ajax from you guys.
I dont' understand how the actual query is made to the database to get the data u want.

I want to auto fill some html fields when I select different options from a drop down menu. The drop down options have an id for a 'work order' or 'task' associated with them... when one is selected I want to use ajax to get the number of hours and hourly rate assigned to that work order and get the total. so the query would be (select hours, time from work_order where id=woId)

I was told by someone else about the prototype framework for ajax and am trying to use that.

using the prototype library i have this ....

new Ajax.Updater('estimatedBill_'+dynId,'ajaxRequest.html', {
    method : 'get',
    parameters: {}
});

I just dont understand how or where to put my query so that ajax returns the correct information.

If you can help me using the protype libraries that would be great but any kind of help would be much appreciated.

Thanks!

[schmidty]

anyone?