Query based on dates - mysql

Question

I've got the following table/data (example)
Users
user_id | email
1 | asd#asd.com
2 | asd2#asd.com
3 | asd3#asd.com
4 | asd4#asd.com
5 | asd5#asd.com
Scheduled_Jobs
job_id | user_id | date
1 | 1 | 05/09/2019
2 | 1 | 05/10/2019
3 | 1 | 05/11/2019
4 | 1 | 05/12/2019
5 | 2 | 07/10/2019
6 | 2 | 07/11/2019
7 | 2 | 07/12/2019
8 | 3 | 11/07/2019
9 | 4 | 13/10/2019
10 | 4 | 13/11/2019
11 | 5 | 10/10/2019
12 | 5 | 10/11/2019
13 | 5 | 10/12/2019
Last_Update
update_id | job_id
1 | 1
2 | 2
3 | 3
4 | 5
5 | 9
6 | 11
When a user is created a list of scheduled jobs is created too. When a user completes a job the Last_Update table is getting updated.
I'm trying to show a list of users which got unfinished jobs based on date. For example 1-30 days delay: x users, 31-60 days delay: y users etc
Based on the example above here would be the expected result:
Number of users with no delayed jobs: 2 (users 1 & 4)
1-30 days delay: 2 (users 2 & 5)
31-60 days delay: 0
Over 60 days delay: 1 (user 3)
I'm currently only showing the number of users that got no delayed jobs
SELECT u.user_id
FROM users u
LEFT JOIN (
SELECT j.user_id AS completed
FROM jobs j
LEFT JOIN last_update lu
ON lu.job_id = j.job_id
WHERE j.job_date <= CURDATE()
AND lu.update_id IS NULL
) AS cj
ON u.user_id = cj.completed
WHERE cj.completed IS NULL

Answer 1

You can first join the three tables, aggregate by user_id and compute, for each user
how many unfinished jobs they have
how many unfinished jobs they have within the last 30 days
how many unfinished jobs they have within the last 31-60 days
Then, you can add another level of aggreation and count how many users meet each criteria.
Query:
select
sum(cnt_jobs_unfinished = 0) cnt_users_no_unfinished_jobs,
sum(cnt_jobs_unfinished_30d > 0) cnt_users_unfinished_30d,
sum(cnt_jobs_unfinished_31_60d > 0) cnt_users_unfinished_31_60d
from (
select
u.user_id,
sum(l.job_id is null) cnt_jobs_unfinished,
sum(
l.job_id is null
and j.date >= curdate() - interval 30 day
) cnt_jobs_unfinished_30d,
sum(
l.job_id is null
and j.date < curdate() - interval 30 day
and j.date >= curdate() - interval 60 day
) cnt_jobs_unfinished_31_60d
from users u
inner join scheduled_jobs j
on j.date <= curdate()
and j.user_id = u.user_id
left join last_update l
on l.job_id = j.job_id
group by u.user_id
) t
Demo on DB Fiddle
cnt_users_no_unfinished_jobs | cnt_users_unfinished_30d | cnt_users_unfinished_31_60d
---------------------------: | -----------------------: | --------------------------:
2 | 2 | 1
Note: I had to modify your sample data so job 8, for user 3, has a date within 30-60 days, as it was not the case in your original data).
You can run the subquery independantly to see what it returns:
user_id | cnt_jobs_unfinished | cnt_jobs_unfinished_30d | cnt_jobs_unfinished_31_60d
------: | ------------------: | ----------------------: | -------------------------:
1 | 0 | 0 | 0
2 | 1 | 1 | 0
3 | 1 | 0 | 1
4 | 0 | 0 | 0
5 | 1 | 1 | 0