将函数返回传递给同一行中的另一个函数 [英] Pass a function return to another in the same row

问题描述

我需要传递在前一列中选择的函数的返回值，并将其作为参数传递给同一行中的后续函数。我不能使用别名：

我想要的是：

  SELECT 
 dbo.GetSecondID（f.ID）作为SecondID，
 dbo.GetThirdID（SecondID）作为ThirdID 
 FROM Foo f 
  

任何解决方法？谢谢！

编辑：

方法 dbo.GetSecondID（）非常重，我正在处理表中的几百万条记录。将方法作为参数传递是不明智的。

解决方案

宾果！应用 CROSS APPLY 的秘诀。以下代码很有用：
$ b $ pre $ SELECT
sndID.SecondID，
dbo.GetThirdID（sndID.SecondID） as ThirdID
FROM Foo f
CROSS APPLY
（
SELECT dbo.GetSecondID（f.ID）as SecondID
）sndID




这只适用于 SecondID 是唯一的（只返回一条记录）或 GROUP BY 被使用

I Need to pass the return value of a function that is selected in previous column and pass it as parameter to a following function in the same row. I cannot use the alias:

What I want to have is:

SELECT
    dbo.GetSecondID(f.ID) as SecondID,
    dbo.GetThirdID(SecondID) as ThirdID
FROM Foo f

Any workaround? Thank you!

EDIT:

The method dbo.GetSecondID() is very heavy and I am dealing with a couple of million records in the table. It is not wise to pass the method as a parameter.

解决方案

Bingo! The secret stand in applying a CROSS APPLY. The following code was helpful

SELECT
    sndID.SecondID,
    dbo.GetThirdID(sndID.SecondID) as ThirdID
FROM Foo f
CROSS APPLY
(
    SELECT dbo.GetSecondID(f.ID) as SecondID
) sndID

EDIT:

This only works if SecondID is unique (only one record is returned) or GROUP BY is used

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