Count over previously defined alias

【问题标题】：Count over previously defined aliasCount over previously defined alias
【发布时间】：2022-12-02 07:34:20
【问题描述】：

I'm trying to avoid writing twice the EXTRACT condition. There is any way to do that? Count over the previous alias apparently is not valid.

SELECT EXTRACT(DECADE FROM to_date(released_year::text, 'yyyy')) AS decade, 
    count(decade) AS total_by_decade
FROM album ...

【问题讨论】：

no you can avoid it, you can only make a cte

标签： sql postgresql

【解决方案1】：

Basically you can avoit it completely, but you can make a CTE

WITH
 CTE as(
SELECT EXTRACT(DECADE FROM to_date(released_year::text, 'yyyy')) AS decade 
 
FROM album ...)
SELECT  decade,  count(decade) AS total_by_decade FROM CTe GROUP BY decade

【讨论】：