无法按别名过滤

Question

created_at - 使用 timzone

键入时间戳

查询：

 select id, 
           created_at,
           extract(epoch from CURRENT_TIMESTAMP - created_at) as delta_sec
    from shop_order

成功的工作。不错

现在我只想显示 delta_sec > 10000

的记录

我试试这个：

select id, 
       created_at,
       extract(epoch from CURRENT_TIMESTAMP - created_at) as delta_sec
from shop_order
where delta_sec > 10000

但是我得到错误：

ERROR:  column "delta_sec" does not exist
LINE 5: where delta_sec > 10000
              ^
SQL state: 42703
Character: 125

Answer 1

只需重复表达式而不是使用其别名，例如：

select 
  id, 
  created_at,
  extract(epoch from CURRENT_TIMESTAMP - created_at)
from shop_order
where extract(epoch from CURRENT_TIMESTAMP - created_at) > 10000

如果您担心数据库将运行表达式两次并因此减慢您的查询速度：请放心，让 PostgreSQL 来处理它。

Answer 2

或者，如果要使用别名进行过滤，则先将数据放入 CTE 中：

WITH cte_name AS (
     SELECT
      id, 
      created_at,
      extract(epoch from CURRENT_TIMESTAMP - created_at) as delta_sec
    FROM shop_order
)
SELECT *
    FROM cte_name
    WHERE delta_sec > 10000

无法按别名过滤

Can't filter by alias

sql

postgresql

where-clause

column-alias