Question

I’d like to get a count of how many times a process code of 20 has a LastModifiedTime before a process code of 10 for each WorkflowId grouping.

This query shows the table layout and some data:

SELECT TOP 10 * 
FROM master.ProcessLogging with (nolock) 
WHERE ProcessCode = 10 OR ProcessCode = 20 
ORDER BY WorkflowId, ProcessCode

I’ve tried a few things, but I’m having a difficult time getting it to work. Each attempt has lead to a dead end that’s not worth posting here. Is there a way to see all of the times a 20 comes before a 10? And maybe even see the time difference between them?

Answer 1

Upon review this will break if more than one 10 in a group

Will there ever be more than 10 in a group and if so how do you want it handled?

SELECT p10.WorkflowId, count(p20.WorkflowId)
FROM master.ProcessLogging p10 
left outer join master.ProcessLogging p20
  on  p20.WorkflowId = p10.WorkflowId
  and p20.EventTime < p10.EventTime
  and p20.ProcessCode = 20
where p10.ProcessCode = 10 
group by p10.WorkflowId 
order by p10.WorkflowId

— Edit from Bob Horn —

Slightly modified above query to show the largest time difference between the 10s and 20s.

SELECT p10.WorkflowId, min(p20.WorkflowId), 
       DATEDIFF(ms, min(p10.lastmodifiedtime), min(p20.lastmodifiedtime)) as 'Diff (ms)'
FROM master.ProcessLogging p10 
join master.ProcessLogging p20
  on  p20.WorkflowId = p10.WorkflowId
  and p20.EventTime < p10.EventTime
  and p20.ProcessCode = 20
where p10.ProcessCode = 10 
group by p10.WorkflowId 
order by ABS(DATEDIFF(ms, min(p10.lastmodifiedtime), min(p20.lastmodifiedtime))) DESC