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SQL question, Can I do something like Rest and Most
I need some help not directly related to doing something in Mathematica, but rather in SQL (another functional language) and wondered if anyone here had some insight into it. I have a simple data base table "timeseries" with three fields id values datetime The table has a few thousand rows of data I need to calculate the ratio of each value to its previous value. In Mathematica I'd sort values by datetime than do something simple like Most[values] / Rest[values] I wondered if anyone had any idea of how to do this efficiently in SQL? Also, if anyone has any recommendation for an SQL forum comparable to what this forum provides for Mathematica. Please advise. (Even as I ask the question I realize that I've never seen anything as helpful or as sophisticated as this forum in any other subject area, but I can always hope). Thanks to all.