在SQL计算中使用别名 [英] Using an Alias in SQL Calculations
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问题描述
为什么此查询不起作用?
Why won't this query work?
SELECT 10 AS my_num, my_num*5 AS another_number
FROM table
在此示例中,我试图在其他计算中使用my_num别名。这导致未知列my_num
In this example, I'm trying to use the my_num alias in other calculations. This results in unknown column "my_num"
这是我想要做的简化版本,但基本上我想使用别名进行其他计算。我的计算要复杂得多,这就是为什么它别名,因为我重复几次不同的方式。
This is a simplified version of what I am trying to do, but basically I would like to use an alias to make other calculations. My calculations are much more complicated and thats why it would be nice to alias it since I repeat it several times different ways.
推荐答案
只需用(SELECT alias)包装重复使用的别名:
Simply wrap your reused alias with (SELECT alias)
:
SELECT 10 AS my_num,
(SELECT my_num) * 5 AS another_number
FROM table
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