如何重用计算列避免重复sql语句? [英] How to reuse calculated columns avoiding duplicating the sql statement?

问题描述

我有很多计算过的列，它们不断重复，一个在其他列中，包括嵌套的 case 语句.

I have a lots of calculated columns and they keep repeting themselves, one inside of the others, including nested cases statements.

我正在寻找一种方法来做某事的真正简化版本.

There is a really simplified version of something that i've searching a way to do.

SELECT 
    (1+2) AS A, 
    A + 3 AS B, 
    B * 7 AS C 
FROM MYTABLE

提前致谢.

推荐答案

你可以尝试这样的事情.

You could try something like this.

SELECT 
    A.Val AS A, 
    B.Val AS B, 
    C.Val AS C 
FROM MYTABLE
  cross apply(select 1 + 2) as A(Val)
  cross apply(select A.Val + 3) as B(Val)
  cross apply(select B.Val * 7) as C(Val)

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