SQL Server中的多线程 [英] Multi-threading in SQL Server

问题描述

让我们说我有一个像这样的表:

Lets say I have a table like:

a     b    c     d    e      f
---------------------------------
1.2  2.3  4.4   5.1  6.7    11.9   
7.2  2.3  4.3   5.1  4.7    3.9   
1.9  5.3  3.3   5.1  3.7    8.9   
5.2  2.7  7.4   9.1  1.7    2.9  

如果我必须计算列总和的乘方的平方根

If I have to compute something as the sqrt of the multiplication of the sum of the columns

SQRT(sum(a*a)),SQRT(sum(a*b)),SQRT(sum(a*c)),SQRT(sum(a*d)),SQRT(sum(a*e)),SQRT(sum(a*f)),SQRT(sum(b*b)),SQRT(sum(b*c)),SQRT(sum(b*d))....SQRT(sum(f*f))

• 如何使用threads(在此 案例我猜有6个线程)来解决 并插入新表?
• 如果我不知道 表中的列，有没有办法 创建线程取决于 列数，当然知道阈值(例如，不超过10个线程)?
• How could I use threads (in this case I guess 6 threads) to solve this and insert in a new table?
• And if I do not know the number of columns in the table, is there a way to create threads depending on the number of columns, of course knowing a threshold (for example not more than 10 threads)??

目前我有类似的东西

SELECT SQRT(sum(a*a)),SQRT(sum(a*b)), .... ,SQRT(sum(f*f)) INTO TEMP FROM a_table

推荐答案

问题是您的架构与您要提取的信息类型不匹配，因此为什么很难获得所需的信息.在这种情况下，这些值将不被标准化.如果将它们标准化，查询将变得很简单:

The problem is that your schema does not match to the type of information you wish to extract which why getting the information you want is such a pain. In this case, the values are not normalized. If you normalize them, the query becomes trivial:

With Inputs As
    (
    Select 1 As RowNum, 1.2 As a, 2.3 As b, 4.4 As c, 5.1 As d, 6.7 As e, 11.9 As f
    Union All Select 2, 7.2, 2.3, 4.3, 5.1, 4.7, 3.9   
    Union All Select 3, 1.9, 5.3, 3.3, 5.1, 3.7, 8.9   
    Union All Select 4, 5.2, 2.7, 7.4, 9.1, 1.7, 2.9 
    )
    , NormalizedInputs As
    (
    Select RowNum, 'a' As ColName, a As Value From Inputs
    Union All Select RowNum, 'b', b From Inputs
    Union All Select RowNum, 'c', c From Inputs
    Union All Select RowNum, 'd', d From Inputs
    Union All Select RowNum, 'e', e From Inputs
    Union All Select RowNum, 'f', f From Inputs
    )
Select N1.RowNum, Sqrt( Sum( N1.Value * N2.Value ) )
From NormalizedInputs As N1
    Left Join NormalizedInputs As N2
        On N2.RowNum = N1.RowNum
            And N2.ColName >= N1.ColName
Group By N1.RowNum

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