mysql - 如何计算特定月份每天的订阅数量

Question

(使用MySQL)我需要找出特定月份每天有多少人订阅。到目前为止，这是我的查询:

SELECT COUNT(user_ID) AS Subs,  DATE(subscription_date) AS Day_Joined FROM Users GROUP BY DAY(Day_Joined), user_ID HAVING MONTH(Day_Joined) = 03 ORDER BY Day_Joined

我希望输出给我:

subs Day_Joined
- 10   2018-03-04
- 20   2018-03-05
- 30   2018-03-06

到目前为止它给我:

subs Day_Joined
- 5   2018-03-04
- 3   2018-03-04
- 2   2018-03-04
... and so on..

Answer 1

你应该只为 Day_Joined 分组

  SELECT COUNT(user_ID) AS Subs
       , DATE(subscription_date) AS Day_Joined
  FROM Users
  GROUP BY DATE(subscription_date)
  HAVING MONTH(DATE(subscription_date)) = 03
  ORDER BY 

如果你也为 user_id 分组，你没有不同 user_id 的计数..