Nice example, thanks for simplifying this complex subject. Would it have been better to make the node_id column in the table example an identity column for saving data (after a user selected one item) and reporting? What are the costs/benefits?

Also, I guess the hierarchy could change too, what if there was an org. change in that example, where Alan left and another became the start of the tree? In my application, do we want to save the pick of Alan in your hierarchy (hence that identity column idea above) or just the current starting node for the year, no matter who it is at that point in time? I guess that may depend on your application needs?

Thanks again for the nice article and great subject.