Combo Box for ASP.NET Web Forms - How to add items to an editor on the client in multi-column mode This example demonstrates how to create a multi-column combo box editor and populate it with items on ...

If you need to add items to a bound combo box dynamically, you must prompt the user to enter data for all required fields, save the new record, and then requery the combo box to display the new value.

allowNewItems attribute Specify whether or not users can add to the list of items that appear in the combo box at run-time. You can also query or set this attribute ...