计算每个月的平均值，不包括带/零的月份

Question

我有以下工作查询，对每个月的长度列/值求和。

SELECT SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 1 THEN (tblcm.Lgth) ELSE 0 END) AS 'Jan',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 2 THEN (tblcm.Lgth) ELSE 0 END) AS 'Feb',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 3 THEN (tblcm.Lgth) ELSE 0 END) AS 'Mar',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 4 THEN (tblcm.Lgth) ELSE 0 END) AS 'Apr',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 5 THEN (tblcm.Lgth) ELSE 0 END) AS 'May',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 6 THEN (tblcm.Lgth) ELSE 0 END) AS 'Jun',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 7 THEN (tblcm.Lgth) ELSE 0 END) AS 'Jul',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 8 THEN (tblcm.Lgth) ELSE 0 END) AS 'Aug',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 9 THEN (tblcm.Lgth) ELSE 0 END) AS 'Sep',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 10 THEN (tblcm.Lgth) ELSE 0 END) AS 'Oct',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 11 THEN (tblcm.Lgth) ELSE 0 END) AS 'Nov',
   SUM(CASE WHEN DATE_FORMAT(tblcm.omActCompDate, '%m') = 12 THEN (tblcm.Lgth) ELSE 0 END) AS 'Dec',
   SUM(tblcm.Lgth) AS Total

给我以下信息：

Jan 13050
Feb 5200
Mar 48450
Apr 34041
May 38000
Jun 0
Jul 0
Aug 0
Sep 0
Oct 0
Nov 0
Dec 0

如何获得仅大于零月份的 AVG？

• 我试过：avg(nullif(tblcm.Lgth, 0)) as m_Avg 但得到 1825

• 我也试过： avg(case when tblcm.Lgth = 0 then null else tblcm.Lgth end) as m_Avg 但也得到 1825

• 我需要得到 27748（这是 1 月到 5 月的总和，除以 5 个月）

Answer 1

我很确定您需要一个子查询来做到这一点。以下假设您的原始查询在发布时是正确的，并且如您所说的那样起作用。这是未经测试的，您可能本可以在您的问题中包含更多详细信息，所以如果这不符合您的需求，现在让我来。

SELECT AVG(sumLgth) AS avgLgth, SUM(sumLgth) AS totalLgth,
    SUM(CASE WHEN theMonth = 1 THEN (tbl.sumLgth) ELSE 0 END) AS 'Jan',
    SUM(CASE WHEN theMonth = 2 THEN (tbl.sumLgth) ELSE 0 END) AS 'Feb',
    ...
FROM (
    SELECT MONTH(omActCompDate) AS theMonth, SUM(lgth) AS sumLgth
    FROM tblcm
    GROUP BY MONTH(omActCompDate)
    HAVING sumLgth > 0
) tbl