我有以下SQL:(bitemp)
SELECT COUNT (*) AS Count
FROM Table T
WHERE (T.Update_time =
(SELECT MAX (B.Update_time )
FROM Table B
WHERE (B.Id = T.Id))
GROUP BY T.Grouping
现在我得到了一个包含很多数字的结果集。我想要得到这个列表的平均值。目前,我正在将列表导入excel并使用它的平均值函数。但是有一个DB2的AVG函数,但我没有让它工作。
我试过SELECT AVG(COUNT(*))
,也试过SELECT AVG(*) FROM (theQuery)
。
发布于 2011-10-12 17:26:59
您可以将您的查询放入子查询:
SELECT avg(count)
FROM
(
SELECT COUNT (*) AS Count
FROM Table T
WHERE T.Update_time =
(SELECT MAX (B.Update_time )
FROM Table B
WHERE (B.Id = T.Id))
GROUP BY T.Grouping
) as counts
编辑:我认为这应该是相同的:
SELECT count(*) / count(distinct T.Grouping)
FROM Table T
WHERE T.Update_time =
(SELECT MAX (B.Update_time)
FROM Table B
WHERE (B.Id = T.Id))
https://stackoverflow.com/questions/7737869
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