如何计算别名列上的聚合函数SUM? [英] How to calculate aggregate function SUM on an alias column?

问题描述

如何在别名列上计算聚合函数SUM?

How to calculate aggregate function SUM on an alias column?

SELECT a.question_id, 
       a.level, 
       Count(a.question_id) AS rank, 
       Sum(rank)        AS total 
FROM   logs AS a, 
       question AS b 
WHERE  a.question_id = b.q_id 
       AND a.level = '2' 
GROUP  BY a.question_id 
ORDER  BY rank DESC 

推荐答案

用(SELECT别名)简单包装您的重用别名:

Simply wrap your reused alias with (SELECT alias) :

SELECT a.question_id, 
       a.level, 
       COUNT(a.question_id) AS rank, 
       SUM(SELECT(rank)) AS total 
FROM   logs AS a, 
       question AS b 
WHERE  a.question_id = b.q_id 
       AND a.level = '2' 
GROUP  BY a.question_id 
ORDER  BY rank DESC 

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