Jeff,

>I have a nullable column in my database and business object (Guid?). I want to bind this to a ComboBox so the user can select one of the entries or nothing.
>
>I tried checking the SelectedIndex and if it was -1 setting the SelectedValue to null - it wasn't happy.
>
>I then tried setting the BusinessObject value to null - it complained that it needed to be DBNull.Value - which I can't send to the business object.
>
>How do I use databinding to allow the user to select nothing (null) from a ComboBox?

Check out this link (under the topic "How can I add a "null" or "DBNull" entry to my bound ComboBox?":

http://windowsclient.net/blogs/faqs/rss.aspx?Tags=ComboBox&AndTags=1

Best Regards,