For example : I have UserID and UserName. So I use DropDownList. UserName is DataTextField and UserID is DataValueField. So User can choose their name and I save UserID to my database. But If User is new and not registered. I want to allow to type in DropDownList and I save the name to database. So for registered people can choose and not registered people can key in.
How should I do? Can anybody give me suggestions? Thanks