mysql - 在查询中使用 SUM() 结果

Question

我有一个小问题。我正在使用这样的查询:

SELECT SUM(...) AS result1, SUM(...) AS result2 FROM ...

我的问题是如何在表达式中使用 result1 和 result2，如下所示:

SELECT SUM(...) AS result1, SUM(...) AS result2, result1*100/result2 AS percentage FROM ...

---

有没有办法只使用 SUM() 函数或其他函数的结果？

我已经像上面那样尝试过了，但是这会返回一个错误。

Answer 1

有两种方法，要么需要重复整个表达式求和，要么使用子选择

SELECT SUM(first_col) AS result1, SUM(second_col) AS result2 
SUM(first_col) * 100 /SUM(second_col) percentage 
FROM ...

或者子选择

SELECT result1, result2 , result1*100/result2 AS percentage 
FROM (
SELECT SUM(first_col) AS result1, SUM(second_col) AS result2 
FROM ...
) t