Question

I have 2 tables:

Table workflow

Request_Id, Step ID
123, 4
123, 7
198, 5

Table Steps

Step_Id, Step_num
4, 30
7, 12
5, 172

I am trying to return all records in table Workflow, where Steps.step_num is the max for that record.
My result should look like this:

Request_Id, Step_Id, Step_Num
123, 4, 30
198, 5, 172

I’ve tried this, but I don’t get the right Step_ID:

select request_id, step_id,max(step_num) from
(
select ww.request_id as request_id, ww.step_id as step_id, st.step_num as step_num
from workflow ww
left join steps st on ww.step_id=st.step_id) as s
group by request_id

Please help, I am stuck 🙂

Answer 1

SELECT  *
FROM    (
        SELECT  DISTINCT request_id
        FROM    workflow
        ) wd
JOIN    steps s
ON      s.step_id =
        (
        SELECT  si.step_id
        FROM    workflow wi
        JOIN    steps si
        ON      si.step_id = wi.step_id
        WHERE   wi.request_id = wd.request_id
        ORDER BY
                stem_num DESC
        LIMIT 1
        )