wbrianwhite (5/12/2009)
In what way was simple set logic unable to perform this operation? It looks like this could be solved with left outer joins and is null tests. I don't have the test db mentioned, so my > may be wrong, it could need to be a <, I can never remember without testing it. But something like this should do the trick
I think it's just a matter of ...elegance? To me using Row_Number() statements (and CTEs in general) are easier to write and easier to follow in specific situations (provided the one reading knows what they do). And I can tell you just from testing this morning that the Row_Number() query has a performance improvement over the left joins and isnull tests I had been using previously.