Question

There are two Comboboxs, one button, and a GridView in a page.

When I click the button, the selected items of the Comboboxs should be inserted to the GridView and at the same time updated in database.

When I click the button it should not perform a postback. Users should be able to add lots ot records when hitting the submit button.

Answer 1

Here is what you need to do:

1. Set a script function call in OnClientClick and return false from this method.
   http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx
2. In this client method use JQuery AJAX to call a web method to update the db.
   http://encosia.com/using-jquery-to-directly-call-aspnet-ajax-page-methods/
3. Add a row to the table with jquery methods that manipulate DOM.
   Add table row in jQuery

Of course you can use an UpdatePanel but you have to insert the combo and the grid inside, so this is not going to save you server CPU and traffic.