在SQL中计算移动平均值 [英] Calculate moving averages in SQL
问题描述
我想从MySQL列中计算12个月的移动平均值.数据代表时序功率测量,它是一个比较大的数据集(几年中每10分钟一次).高性能查询会很好,但是速度是我以后可以解决的问题.
I want to calculate a 12 month moving average from a MySQL column. The data represents time-series power measurements, it is a largish dataset (every 10 minutes for 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
以下查询为我提供了每月的总活动量:
The following query gives me the total Active 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)
以下查询为我提供了给定月份和年份的移动平均有效-例如2011年10月
The following query gives me the moving average Active 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)
但是我想生成一个查询,该查询在下一列中返回月总计和12个月移动平均值.
I would however like to generate a query which returns the monthly total and the 12 month moving average in the next column.
year month total average
2012 2 701474 9258089
2012 1 877535 9386664
... etc
(因数6是因为数据代表每10分钟记录的瞬时功率,将总功率除以6得到总能量)
(The factor of 6 is because the data represents instantaneous power recorded every 10 minutes, dividing the total by 6 gives the total energy)
推荐答案
尝试:
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)
这篇关于在SQL中计算移动平均值的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!