MySQL 计算一天内第一条初始收到消息和第一条回复之间的平均时间

Question

我有三个 table，名为 chats、chat_members 和 chat_messages。我想获得一天内第一次收到消息和第一次回复之间的平均时间。

chat_members

|chat_id|user_id|
-----------------
|   1   |   3   |
|   1   |   4   |
|   2   |   3   |
|   2   |   6   |

chat_messages

|chat_id|sender_id|      body    |     created_at     |
------------------------------------------------------|
|   1   |   4     |"initial 1   "|2019-06-30 10:31:16 |
|   1   |   3     |"answer day 1"|2019-06-30 10:52:56 |
|   2   |   6     |"initial ans" |2019-06-30 10:54:33 |
|   2   |   3     |"answer"      |2019-06-30 10:56:30 |
|   1   |   4     |"initial 2"   |2019-07-01 09:30:02 |
|   1   |   3     |"answer day 2"|2019-07-01 09:45:02 |

预期结果：特定用户的平均响应时间。假设 user_id: 3 的平均响应时间为 17.5 minutes。

|chat_id|avg_minutes|
--------------------|
|   1   |   20      |
|   2   |   15      |

将其视为 facebook 页面的平均响应时间：

“Response time is the average time it takes your Page to send initial responses to new messages in one day.”

Answer 1

这是一个中间答案...

DROP TABLE IF EXISTS chat_messages;
CREATE TABLE chat_messages
(message_id SERIAL PRIMARY KEY
,chat_id INT NOT NULL
,sender_id INT NOT NULL
,body VARCHAR(255) NOT NULL
,created_at DATETIME NOT NULL
);

INSERT INTO chat_messages VALUES
(1,1,4,'initial 1','2019-06-30 10:31:16'),
(2,1,3,'answer day 1','2019-06-30 10:52:56'),
(3,2,6,'initial ans','2019-06-30 10:54:33'),
(4,2,3,'answer','2019-06-30 10:56:30'),
(5,1,4,'initial 2','019-07-01 09:30:02'),
(6,1,3,'answer day 2','2019-07-01 09:45:02');

SELECT x.*
     , y.sender_id responder
     , MIN(y.created_at) response 
  FROM chat_messages x 
  JOIN chat_messages y 
    ON y.chat_id = x.chat_id 
   AND y.created_at > x.created_at 
   AND y.sender_id <> x.sender_id 
 GROUP 
    BY x.message_id,y.sender_id;
+------------+---------+-----------+-------------+---------------------+-----------+---------------------+
| message_id | chat_id | sender_id | body        | created_at          | responder | response            |
+------------+---------+-----------+-------------+---------------------+-----------+---------------------+
|          1 |       1 |         4 | initial 1   | 2019-06-30 10:31:16 |         3 | 2019-06-30 10:52:56 |
|          3 |       2 |         6 | initial ans | 2019-06-30 10:54:33 |         3 | 2019-06-30 10:56:30 |
|          5 |       1 |         4 | initial 2   | 0019-07-01 09:30:02 |         3 | 2019-06-30 10:52:56 |
+------------+---------+-----------+-------------+---------------------+-----------+---------------------+

这为我们提供了每个响应者最早响应的时间。

接下来，我们可以汇总 created_at 和响应之间的差异，但我会将其留作 reader 的练习。

MySQL 计算一天内第一条初始收到消息和第一条回复之间的平均时间

MySQL Calculate average time between first initial received message and the first answer in one day

mysql

mysql-5.7