MySQL 在 Windows 上给了我“未知列”错误答案

【问题标题】：MySQL gives me "unknown column" error on WindowsMySQL 在 Windows 上给了我“未知列”错误
【发布时间】：2021-06-10 13:33:19
【问题描述】：

我使用 MySQL 在 Node.Js 上执行了以下查询：

SELECT COUNT(DISTINCT t.uid) AS usersCount, COUNT(*) AS workingDaysCount
    FROM (
    SELECT d.date, u.id AS uid,
        CASE TIMESTAMPDIFF(day, SUBDATE(d.date, WEEKDAY(d.date)), d.date)
            WHEN 0 THEN w.monday
            WHEN 1 THEN w.tuesday
            WHEN 2 THEN w.wednesday
            WHEN 3 THEN w.thursday
            WHEN 4 THEN w.friday
            WHEN 5 THEN w.saturday
            WHEN 6 THEN w.sunday
            ELSE NULL
        END AS working_day
    FROM (
    SELECT date_range.date
    FROM (
        SELECT CURDATE() - INTERVAL (sign.a * (a.a + (10 * b.a) + (100 * c.a) + (1000 * e.a) )) DAY AS date
        FROM (SELECT -1 AS a UNION ALL SELECT 1) AS sign
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS a
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS b
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS c
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS e
        ORDER BY date DESC
    ) date_range
    WHERE date_range.Date BETWEEN DATE('2021-06-10') AND DATE('2021-06-10')) d, users u
        LEFT OUTER JOIN working_days w ON w.id = (
            SELECT id
            FROM working_days
            WHERE user_id = u.id AND week_start_date <= d.date
            ORDER BY week_start_date DESC
            LIMIT 1
        )
    WHERE u.id IN (4)
    GROUP BY d.date, u.id
) t
    WHERE t.working_day = 1;

在 Linux 服务器上它工作正常，所以我不知道问题出在哪里，但在 Windows 上我有以下错误：

#1054 - Unknown column 'd.date' in 'where clause'

我已经查看了代码并调试了几个小时，但我没有找到任何关于此的答案。请问有人有什么想法吗？

【问题讨论】：

也许我遗漏了一些东西，但我没有看到表别名 d 的定义。 MySQL 会同意这一点，我应该注意。
@GordonLinoff 我想这应该像别名 WHERE date_range.Date BETWEEN DATE('2021-06-10') AND DATE('2021-06-10')) d, users u
DISTINCT 不是一个函数，它是一个集合量词！跳过那些多余的括号，直接写COUNT(DISTINCT t.uid) 让代码更清晰。
LEFT OUTER JOIN 的ON 子句只能访问u 和w 列。当您混合使用显式 JOIN 和隐式的逗号分隔连接时，就会发生这种情况。到处切换到显式JOIN，问题就消失了！
顺便说一句，您的 Windows MySQL 版本可能比 Linux 版本新，并且该行为已得到纠正。

标签： javascript mysql sql node.js

【解决方案1】：

问题点在于用逗号和 JOIN 组合笛卡尔。

别名为t 的子查询看起来像

SELECT ...
FROM (...) d, u LEFT OUTER JOIN working_days w ...

逗号优先级低于JOIN优先级，因此查询为

SELECT ...
FROM (...) d, ( u LEFT OUTER JOIN working_days w ... )

即u 和 w 首先加入。当然，此时子查询d是不可访问的。

用 CROSS JOIN 替换逗号：

SELECT ...
FROM (...) d
CROSS JOIN u 
LEFT OUTER JOIN working_days w ...

【讨论】：