Populating a span based on input field

[ravicoder]

Hi all

I have a login form containing USERID (input type text), Username (span) and password. I want the Username span to be populated with the User Name retrieved from a database based on the entered User ID. Could someone point me in the right direction as to how to run an ajax script and do the needful? some sample code will help

Any help will be appreciated

Thanks
Ravi Bangera