查询MySQL将按照月份和每周返回用户创建的帖子的平均值。

要查询MySQL按月份和每周返回用户创建的帖子的平均值，首先需要创建一个包含用户创建帖子日期的表。

创建一个名为post的表，包含以下字段：

• id：帖子的唯一标识符（主键）
• user_id：用户的唯一标识符
• created_at：帖子创建的日期时间

CREATE TABLE post (
  id INT PRIMARY KEY AUTO_INCREMENT,
  user_id INT,
  created_at DATETIME
);

插入一些示例数据：

INSERT INTO post (user_id, created_at) VALUES
  (1, '2022-01-01 09:00:00'),
  (1, '2022-01-07 10:00:00'),
  (2, '2022-01-01 11:00:00'),
  (2, '2022-01-02 12:00:00'),
  (2, '2022-01-08 13:00:00');

接下来，使用以下查询来计算每个月和每周的帖子平均值：

按月份查询：

SELECT
  YEAR(created_at) AS year,
  MONTH(created_at) AS month,
  AVG(COUNT(*)) AS average_posts
FROM post
GROUP BY YEAR(created_at), MONTH(created_at)
ORDER BY YEAR(created_at), MONTH(created_at);

按每周查询：

SELECT
  YEAR(created_at) AS year,
  WEEK(created_at) AS week,
  AVG(COUNT(*)) AS average_posts
FROM post
GROUP BY YEAR(created_at), WEEK(created_at)
ORDER BY YEAR(created_at), WEEK(created_at);

这样，你将获得按月份和每周返回用户创建的帖子的平均值的结果。