在WHERE子句中引用列名别名 [英] Refer to a column name alias in the WHERE clause

问题描述

我在Postgres sql中用列别名记录了此查询，它工作正常：

I have written down this query in postgres sql with column alias it is working fine:

select email as e from users 

它在 e 列别名下显示结果但是当我用 e 触发 where 条件时，它显示此错误：

It displays me result under e column alias but when I fire where condition with e then it shows this error:

select email as e from users where e = '[e-mail]'

错误：列 e不存在

ERROR: column "e" does not exist

为什么？

推荐答案

其中被评估的地方在 select 之前，因此您不能使用在 where select 中声明的别名。 c $ c>子句。

where is evaluated before select, so you can't use alias declared in select in where clause.

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