MySQL-左连接中出现错误1064

我目前正在尝试仅使用MySQL查询来格式化数据。我不想用编程语言来操纵它。所有操作仅在一个表上完成

我的问题是：

    SELECT DATE(datetime_column) AS date, COUNT(`id`) AS users_a FROM users a 
    WHERE datetime_column >= '2017-12-01' GROUP BY DATE(datetime_column), rank HAVING rank = "good"

    LEFT JOIN (SELECT DATE(datetime_column) AS date, COUNT(`id`) AS users_b FROM users
    WHERE datetime_column >= '2017-12-01' GROUP BY DATE(datetime_column), rank HAVING rank = "bad") AS b 
    ON b.date = a.date;

输出应如下所示：

date users_a users_b 2017-12-01 17 20 2017-12-02 4 9 如果这两个查询单独执行，它们会给出准确的结果，我只希望数据位于一个表中。但是，我得到以下错误：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LEFT JOIN (SELECT DATE(datetime) AS date, COUNT(`id`) AS users_b FROM ' at line 2 试试这个

SELECT DATE(datetime_column) date, SUM(CASE WHEN rank = "good" THEN 1 END) users_a, SUM(CASE WHEN rank = "bad" THEN 1 END) users_b
FROM users
WHERE datetime_column>= '2017-12-01'
GROUP BY DATE(datetime_column)

联接必须在HAVING子句之前发生

根据MySQL选择：

此外，您还可以将其简化为：

SELECT
    DATE(`datetime_column`) AS `date`, 
    SUM(IF(`rank` = 'good', 1, 0)) AS `users_a`,
    SUM(IF(`rank` = 'bad', 1, 0)) AS `users_b`
FROM
    `users`
WHERE
   datetime_column >= '2017-12-01'
GROUP BY
    DATE(datetime_column)

---

这会为每个“好”用户增加一列用户，为每个“坏”用户增加一列用户。

我喜欢这个简洁完美的解决方案！谢谢你，谢谢你的帮助。很好

SELECT
    DATE(`datetime_column`) AS `date`, 
    SUM(IF(`rank` = 'good', 1, 0)) AS `users_a`,
    SUM(IF(`rank` = 'bad', 1, 0)) AS `users_b`
FROM
    `users`
WHERE
   datetime_column >= '2017-12-01'
GROUP BY
    DATE(datetime_column)