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滑动聚合是按顺序对滑动窗口范围内的数据进行聚合的操作。下累积聚合不同，滑动聚合并不是统计开始计算的位置到当前位置的数据。
SELECT
a.empid,
DATE_FORMAT(a.ordermonth, ‘%Y-%m‘) AS ordermonth,
a.qty AS thismonth,
SUM(b.qty) AS total,
CAST(AVG(b.qty) AS DECIMAL(5,2)) AS avg
FROM emporders a
INNER JOIN emporders b
ON a.empid=b.empid
AND b.ordermonth > DATE_ADD(a.ordermonth, INTERVAL -3 MONTH)
AND b.ordermonth <= a.ordermonth
WHERE DATE_FORMAT(a.ordermonth,‘%Y‘)=‘2015‘ AND DATE_FORMAT(b.ordermonth,‘%Y‘)=‘2015‘
GROUP BY a.empid,DATE_FORMAT(a.ordermonth, ‘%Y-%m‘),a.qty
ORDER BY a.empid,a.ordermonth
SELECT
a.empid,
a.ordermonth AS ordermonth,
a.qty AS thismonth,
SUM(b.qty) AS total,
CAST(AVG(b.qty) AS DECIMAL(5,2)) AS avg
FROM emporders a
INNER JOIN emporders b
ON a.empid=b.empid
AND b.ordermonth > DATE_ADD(a.ordermonth, INTERVAL -3 MONTH)
AND b.ordermonth <= a.ordermonth
WHERE DATE_FORMAT(a.ordermonth,‘%Y‘)=‘2015‘ AND DATE_FORMAT(b.ordermonth,‘%Y‘)=‘2015‘ AND a.empid=1
GROUP BY a.empid,DATE_FORMAT(a.ordermonth, ‘%Y-%m‘),a.qty
HAVING MIN(b.ordermonth)=DATE_ADD(a.ordermonth, INTERVAL-2 MONTH)
ORDER BY a.empid,a.ordermonth
运行结果如下
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原文地址：http://www.cnblogs.com/chenqionghe/p/4679750.html
