DataSource Controls :: For Each Row In Select Statement - Exec Stored Procedure

Ive been banging my head against the wall for the last 2 days with this query I am trying to produce. I have an application that creates requests and these requests have status codes dependant on how far along in the process they are : new request, awaiting approval, approved, in progress, complete When a request is moved to the next status, it Inserts a row into an auditing table, so we can track who moved it onto the next status, along with a timestamp. There are Service Level Agreements in place that mean that a request that is currently 'In Progress' must be actioned to 'Complete' within 5 days. I have been asked to create a query that will return all records that fall outside of this SLA. My main problem is trying to Select the time from the audit log for 'In Progress' and 'Complete' status codes. It would be simple if i only had to find one of the times, as i could add a "WHERE StatusCode = 'complete' clause to the query My Audit table is structured as follows:

[RequestID] [Request Status] [UserID] [CreateDate]

So far I have been successful in querying the table by using the DATEDIFF() function as below:

SELECT
DateDiff
(day,
( SELECT
top 1 CreateDate
FROM audit_tblRequest
WHERE RequestStatus
= 'In Progress'
AND RequestID
=
@RequestID Order
by CreateDate
DESC)
,(SELECT
top 1 CreateDate
FROM audit_tblRequestWHERE RequestStatus
= 90AND RequestID
=@RequestID
Order
by CreateDate
DESC)
)

This will return the difference in days to me, however, i cannot figure out how to integrate this into a query that will be run across all RequestIDs. I was wondering if there was any way to bundle the DateDiff function into a stored Procedure and be able to call it For Each RequestID in the result set I would need to pass the requestID as a parameter, and also add some If Else logic to only return records outside of the 5 Day SLA. Im sure there are some patches in the above logic, but my brain is about to explode and I needed to type it all out before calling it a day for today.