Mysql 如何从其他子查询中选择从字段别名派生的某些数据

我有一个具有以下结构的查询：

SELECT *,
    (<sub-query>) AS `n_acts`,
    (<sub-query>) AS `n_ops`,
    `n_acts`/`n_ops` AS `score`
FROM `user`
WHERE `type` = '3'

为什么MySQL不能识别我的字段别名？我如何解决这个问题？最重要的是，建议这样做吗？

试试这个

SELECT `inner_sub`.`n_acts`, `inner_sub`.`n_ops`, `inner_sub`.`n_acts`/`inner_sub`.`n_ops` AS `score`
FROM
    (SELECT *,
        (<sub-query>) AS `n_acts`,
        (<sub-query>) AS `n_ops`
    FROM `user`
    WHERE `type` = '3') AS `inner_sub`
ORDER BY `inner_sub`.`score` DESC
LIMIT 10

---

在获得所有通过WHERE条件的行之后，DBMS尝试将每一行独立地投影到关键字“SELECT”后面提到的“fields”集合中，集合中的元素“fields”之间不能有任何关联。这就是我对流程的理解。

SELECT `inner_sub`.`n_acts`, `inner_sub`.`n_ops`, `inner_sub`.`n_acts`/`inner_sub`.`n_ops` AS `score`
FROM
    (SELECT *,
        (<sub-query>) AS `n_acts`,
        (<sub-query>) AS `n_ops`
    FROM `user`
    WHERE `type` = '3') AS `inner_sub`
ORDER BY `inner_sub`.`score` DESC
LIMIT 10