I can second what Jeff said about performance of LAG/LEAD as I've done some testing myself. Frankly I was not impressed in the admittedly limited testing that I have done, even though they do tend to make the code look simpler (in some cases).
In this case, I think what Jeff offered looks pretty simple. At least to me. But perhaps I am not objective as I've used that same technique before.
My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.
Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
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