MySQL with Where IN and Distinct and Limit - mysql

Question

SELECT id, server_id, start_time, end_time
FROM errors
WHERE server_id in (3, 12, 24, 25, 26, 27, 28, 29, 30)
ORDER BY id DESC
LIMIT 9
This is the query I'm trying to run to give me results where the server_id = 3, 12, 24, 25, 26, 27, 28, 29, 30. Instead, what I receive is server_id = 25, 25, 12, 25, 27, 27, 28, 28, 27. Note the repeating server_ids. The query gives me unique id but duplicate server_id.
Is there a way I can get results that would show me the last id for each server_id?
I've tried doing ORDER BY server_id but that gives me the same issue.
I tried running DISTINCT but that also does not work.

Answer 1

you'll have to use some aggregation functions.
Something like
select
server_id,
max(id),
avg(start_time),--for example
avg(end_time)--for example
from errors
where server_id in (3, 12, 24, 25, 26, 27, 28, 29, 30)
group by server_id
order by id desc
if you need tht start_time and end_time corresponding to the max id by server_id, you may do
select e.id, e.server_id, e.start_time, e.end_time
from errors e
join (select server_id, max(id) maxid
from errors
group by server_id) t
on t.maxid = e.id and e.server_id = t.server_id
where e.server_id in (3, 12, 24, 25, 26, 27, 28, 29, 30)
order by e.id DESC

Answer 2

The issue you have is that you need only one record from each server with the max ID.. and relative information. You need to limit the results to just that max ID... Here's one way...
SELECT id, server_id, start_time, end_time
FROM errors
WHERE server_id in (3, 12, 24, 25, 26, 27, 28, 29, 30)
and ID = (Select max(ID) from errors E2 where E2.server_ID=errors.server_ID)
ORDER BY id DESC
LIMIT 9