Here is a very good sample for you:
http://msdn2.microsoft.com
Main Topics
Browse All TopicsCan I ask how to implement a linked dropdownlist in GridView?
I don't know how can I dynamically bind the datasource to the 2nd dropdownlist based on the selection of the 1st dropdownlist. Please help with sample code.
This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.
Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.
If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.
Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.
Access the answers to your technology questions today.
30-day free trial. Register in 60 seconds.
Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Try it out and discover for yourself.
30-day free trial. Register in 60 seconds.
Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.
Here is a very good sample for you:
http://msdn2.microsoft.com
Business Accounts
Answer for Membership
by: TheLearnedOnePosted on 2007-11-08 at 05:55:07ID: 20241122
There is the CascadingDropDown control from Microsoft's AJAX control toolkit:
axControlT oolkit/Sam ples/ Casca dingDropDo wn/Cascadi ngDropDown .aspx
Sample:
http://www.asp.net/AJAX/Aj
Bob