That's a fairly broad question. What specific part do you need help with? Making the AJAX call from the browser? Processing the AJAX call in the server? Doing the database access on the server? Processing the response back in the browser? Manipulating the DOM to show the results in the browser? What data reply format are you thinking about using (text, xml, json)? What server side processing technology are you using (jsp, servlet, asp, php)? What database you using? Really -- you are a long way from anyone even trying to help you yet.