To test your understanding of recursion and user-defined functions (UDFs), solve the following puzzle: Can you implement the function ufn_GetSubtree by using a recursive algorithm? Note that you aren't required to return the lvl and path columns, rather just employee details of the whole subtree under a given manager. To find the answer to this puzzle, see the sidebar "Answer to Recursion Challenge," available online at http://www.sqlmag.com, InstantDoc ID 16197.