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SQL Server 中的 MyTable 包含 _TimeStamp、Column1、Column2 和 Column3,它们具有以下值:

_TimeStamp Column1 Column2 Column3  
'2010-10-11 15:55:25.40' 10  3  0.5  
'2010-10-11 15:55:25.50' 20  9  0.7  
'2010-10-11 15:55:25.60' 15  2  1.3  
'2010-10-11 15:55:25.70' 17  8  2.7  
'2010-10-11 15:55:25.80' 42  6  3.6  
'2010-10-11 15:55:25.90' 14  2  0.4  

我想找到 4*Column1*Column2*Column3 的中值。每行的产品是:
60
504
156
1468.8
3628.8
44.8
由于条目数是偶数,中值是两个“中间”条目(156 和 504)的平均值,即 330。另外我只想执行处于选定时间范围内的值的中值,并且解决方案无法更改不是我的数据库。我编辑了一个类似的查询以获得如下所示的查询,但由于列名无效而失败。有什么建议么?

SELECT
  AVG(4*Column1*Column2*Column3)
  FROM 
(
  SELECT
    4*Column1*Column2*Column3,
    ROW_NUMBER() OVER (
    ORDER BY 4*Column1*Column2*Column3 ASC, _TimeStamp ASC) AS RowAsc,
    ROW_NUMBER() OVER (
    ORDER BY 4*Column1*Column2*Column3 DESC, _TimeStamp DESC) AS RowDesc
  FROM MyTable WHERE 
   _TimeStamp BETWEEN '2010-10-11 15:55:25.40' AND '2010-10-11 15:55:25.90' 

) x
WHERE 
  RowAsc IN (RowDesc, RowDesc - 1, RowDesc + 1)
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1 回答 1

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我认为您需要对候选语句做的就是在子查询中为计算值设置别名,然后在外部查询中AVG询问该别名的:

SELECT
  AVG(MyValue)
  FROM 
(
  SELECT
    4*Column1*Column2*Column3 AS MyValue,
    ROW_NUMBER() OVER (
    ORDER BY 4*Column1*Column2*Column3 ASC, _TimeStamp ASC) AS RowAsc,
    ROW_NUMBER() OVER (
    ORDER BY 4*Column1*Column2*Column3 DESC, _TimeStamp DESC) AS RowDesc
  FROM MyTable WHERE 
   _TimeStamp BETWEEN '2010-10-11 15:55:25.40' AND '2010-10-11 15:55:25.90' 

) x
WHERE 
  RowAsc IN (RowDesc, RowDesc - 1, RowDesc + 1)

我还没有测试过这个。

于 2010-10-12T17:55:37.360 回答