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SQL Query - Select Top or Max

Posted on 2011-03-07
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Last Modified: 2012-05-11
Per my client, they need the last HGBA1C Value (which is the o.OBSVALUE) along with the last date that corresponds with this (o.ObsDate). In my query below, I am getting more then one record for a specific patient. How could I just return the patients one date and value versus them all? SELECT TOP 1 maybe? Not 100% sure.

---- Last HGBA1C Value / Date Last HGBA1C Value / (HGBA1C is obs.HDID = 28)

SELECT  o.pid,
        pp.PatientId,
        pp.PatientProfileId,
        dbo.FormatName('', pp.First, pp.Middle, pp.Last, pp.Suffix) AS PatientName,
        MAX(o.OBSDate) AS obsdate,
        o.OBSVALUE
FROM    OBS AS o
        JOIN OBSHEAD AS oh ON o.HDID = oh.HDID
        JOIN PatientProfile AS pp ON o.PID = pp.PId
WHERE   o.HDID = 28
GROUP BY o.PID,
        pp.PatientId,
        pp.PatientProfileId,
        dbo.FormatName('', pp.First, pp.Middle, pp.Last, pp.Suffix),
        o.OBSVALUE

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Question by:Jeff S
6 Comments
 
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Expert Comment

by:Alex Matzinger
ID: 35060962
Use

Select Top 1 [columns you want]
0
 
LVL 142

Assisted Solution

by:Guy Hengel [angelIII / a3]
Guy Hengel [angelIII / a3] earned 100 total points
ID: 35060975
you might want to read this article:
http://www.experts-exchange.com/A_3203.html
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Expert Comment

by:ewangoya
ID: 35061070
SELECT  top 1 o.pid,
        pp.PatientId,
        pp.PatientProfileId,
        dbo.FormatName('', pp.First, pp.Middle, pp.Last, pp.Suffix) AS PatientName,
        MAX(o.OBSDate) AS obsdate,
        o.OBSVALUE
FROM    OBS AS o
        JOIN OBSHEAD AS oh ON o.HDID = oh.HDID
        JOIN PatientProfile AS pp ON o.PID = pp.PId
WHERE   o.HDID = 28
GROUP BY o.PID,
        pp.PatientId,
        pp.PatientProfileId,
        dbo.FormatName('', pp.First, pp.Middle, pp.Last, pp.Suffix),
        o.OBSVALUE
ORDER BY o.OBSVALUE DESC
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Author Comment

by:Jeff S
ID: 35061154
ewangoya -

I started out with 28 records in my data set with multiple patients (some having more then one OBSVALUE. When I use your example, I just get the most recent overall. I want the most recent per distinct patient. I am reading through Angels post and think this may be more in line with what I need, just need to read through it all.
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LVL 40

Accepted Solution

by:
Sharath earned 400 total points
ID: 35063266
try this.
SELECT * 
  FROM (SELECT *, 
               ROW_NUMBER() 
                 OVER(PARTITION BY PatientId ORDER BY obsdate DESC) rn 
          FROM (  SELECT o.pid, 
                         pp.PatientId, 
                         pp.PatientProfileId, 
                         dbo.FORMATNAME('',pp.FIRST,pp.Middle,pp.LAST,pp.Suffix) AS PatientName,
                         MAX(o.OBSDate)                                          AS obsdate, 
                         o.OBSVALUE 
                    FROM OBS AS o 
                         JOIN OBSHEAD AS oh 
                           ON o.HDID = oh.HDID 
                         JOIN PatientProfile AS pp 
                           ON o.PID = pp.PId 
                   WHERE o.HDID = 28 
                GROUP BY o.PID, 
                         pp.PatientId, 
                         pp.PatientProfileId, 
                         dbo.FORMATNAME('',pp.FIRST,pp.Middle,pp.LAST,pp.Suffix), 
                         o.OBSVALUE) t1) t2 
 WHERE rn = 1

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Author Closing Comment

by:Jeff S
ID: 35063355
Thanks!!
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