递归计算mysql中某个时间间隔内的记录

Question

I have a table where records will be getting inserted every 4 hours on a daily basis. If the record was not inserted for continuous 4 hours, I need to insert a log into another table. Below is the table schema.

Id           DocPathid          CreatedAt
1                1              2021-04-02 00:00:00
2                1              2021-04-02 04:00:00
3                1              2021-04-02 09:00:00
4                1              2021-04-02 12:00:00  
5                1              2021-04-02 16:00:00  
6                1              2021-04-02 20:00:00 
7                1              2021-04-02 24:00:00 

In the above case, there was no records inserted within a interval of 4hours (ie between 2021-04-02 04:00:00 & 2021-04-02 09:00:00 ). The query should return no. of failure count (in this case it is failed for 1 time).

Is there a way to achieve this in MySQL?

Answer 1

You can do something like this.

   select count(1)
    from (
      select id, CreatedAt , timestampdiff(hour, CreatedAt  
                 , lead(CreatedAt,1) over (partition by DocPathid order by CreatedAt) ) as hour 
      from Table1  
      ) t
      where hour >4

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=9b0c631145422dbccd2ea23f0a7d2011