Oops. A bit of an oversight there. Those two queries are not logically identical. If you make them <= and >= they are the same.
However, the point I was trying to illustrate still stands. The first one cannot use an index regardless of the projection list. The reason it can't use an index is that you are performing a function (conversion of the data into a new form) on the data and the index is not organized according to the function.
Function based indexes are something Oracle has had for years, I'd like to see MS do a bit of catching up there.
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If most people are not willing to see the difficulty, this is mainly because, consciously or unconsciously, they assume that it will be they who will settle these questions for the others, and because they are convinced of their own capacity to do this. -Friedrich August von Hayek
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