Calculate Moving Averages in SQL
I want to calculate the 12 months moving average from a MySQL column. The data represents power measurements in a time series, this is a fairly large dataset (every 10 minutes over several years). A high performance query would be nice, but speed is something I can work out later.
DTE Active 2012-1-3 00:10 500 2012-1-3 00:20 520 ... etc
The following query gives me the total Asset for each month:
SELECT YEAR(DTE) AS year, MONTH(DTE) AS month, SUM(Active)/6 as total FROM saturne s GROUP BY YEAR(DTE), MONTH(DTE)
The following query gives me the moving average activity for a given month and year - say October 2011.
SELECT SUM(Active)/6 AS average FROM saturne WHERE (YEAR(DTE) = 2011 AND MONTH(DTE) <= 10) OR (YEAR(DTE) = 2010 AND MONTH(DTE) > 10)
I would like, however, to generate a query that returns the total per month and the 12 months moving average in the next column.
year month total average 2012 2 701474 9258089 2012 1 877535 9386664 etc
(Factor 6 is that the data represents the instantaneous power recorded every 10 minutes, dividing the total by 6 gives the total energy)
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SELECT YEAR(GDTE) AS year, MONTH(GDTE) AS month, SUM(case when i=0 then Active end)/6 as total, SUM(Active)/(MAX(i+1)*6) as avg FROM (select s.*, DATE_ADD(DTE, INTERVAL m.i MONTH) GDTE, m.i FROM saturne s cross join (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9 union select 10 union select 11) m ) sq WHERE GDTE <= curdate() GROUP BY YEAR(GDTE), MONTH(GDTE)
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