Comparing two files dates to assign an occurrence number

I have a list of patients (VisitID) who have been restrained.  Some of the patients have multiple eprisodes they are restrained.  The episodes are designated by different order dates and OrderID.

The seconde list are the mandatory 2 hour assessments done by the staff to review the well being of the restrained patients (VisitID) and ActivityDateTime  

What I need to do is compare the Assessment list and assign them to the correct restraint order if the assessment was done (ActivityDateTime) on or after the order date and before a subsequent order date for the same paitent  (VisitID).

I have attached two files of data:  Patients and Assessments.

What is the syntax to create this query?


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Ioannis ParaskevopoulosCommented:

I would love some more data with different assessments and orders, but here is a quick thought:

;WITH PatientsCTE AS
  SELECT  *,
          ISNULL((SELECT  MIN(OrderDateTime) 
                  FROM    Patients 
                  WHERE   VisitID = P.VisitID 
                          AND StartEp > P.StartEp)
                  ,StopOrdDate) AS NextOrderDateTime
  FROM    Patients P
FROM    PatientsCTE P
        JOIN Assessments A
          ON P.VisitID = A.VisitID
          AND A.ActivityDateTime >= P.OrderDateTime 
          AND A.ActivityDateTime < P.NextOrderDateTime

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You may check the results on SQLFiddle.

In the results, the very first assessment is not being returned as it is before the start of the first order. I do not know if it should be returned or not.


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GPSPOWAuthor Commented:
Thank you

I was able to modify your suggestion to meet my table criteria.

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Microsoft SQL Server 2008

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