SQL Server's built-in aggregate functions (e.g., AVG, COUNT, MAX, MIN, SUM) are admittedly useful, but what if you need other types of aggregations that SQL Server doesn't provide? In "Custom Aggregations: The Cursor Technique" (http://www.sqlmag.com, March 2006, InstantDoc ID 49038), I began a discussion of custom aggregations by introducing four classes of solutions and looking closely at one class in particular: the use of cursors. This time, I present a second class of solutions that rely on...