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Query to delete data

Posted on 2013-06-13
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Last Modified: 2013-07-01
I have asked a similar question to this and appologise if you feel you are answering the same question!

I have table with patient treatments. It contains the patient id and the treatment they have had.

create table #TreatmentData(
 
  PatientId nvarchar(18),
TreatedWith nvarchar(30) );

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There are 7 possible treatments.  We can call them A-G.


PatientId    TreatedWith
1                  A
2                  A
3                  B
1                  C
2                  C
4                  E
4                  E
1                  B

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Patients can have any combination of treatments but i am only interested in those that have had "A" and "C"

So i need to delete all patients that have had any other combination of treatments.  

In the table above patient 1 is deleted because he has had treatments A, C and B.
Patient 2 has only had treatments A and C so thats ok.
Patient 3 has had treatment B so is deleted.
Patient 4 has had treatment E so is deleted.

Can someone help with the query?
0
Comment
Question by:soozh
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6 Comments
 
LVL 25

Accepted Solution

by:
chaau earned 250 total points
ID: 39246669
This should do:
DELETE FROM Table1
WHERE PatientID NOT IN
(SELECT PatientID,
COUNT(DISTINCT TreatedWith) AS cnt 
FROM Table1
WHERE TreatedWith IN ('A','C') 
AND 
PatientID NOT IN (SELECT PatientID FROM Table1 WHERE TreatedWith NOT IN ('A','C'))
GROUP BY PatientID
HAVING COUNT(DISTINCT TreatedWith) = 2)

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0
 

Author Comment

by:soozh
ID: 39246776
Thanks.

Quite simple maybe.  

What does "HAVING COUNT( DISTINCT TreatedWith) = 2" do?
0
 
LVL 41

Assisted Solution

by:Sharath
Sharath earned 250 total points
ID: 39246798
Can you try this?
DELETE FROM #TreatmentData t1 
 WHERE NOT EXISTS (SELECT 1 
                     FROM #TreatmentData t2 
                    WHERE t1.PatientID = t2.PatientID 
                    GROUP BY t2.PatientID 
                   HAVING COUNT(DISTINCT t2.TreatedWith) = 2 
                          AND MIN(t2.TreatedWith) = 'A' 
                          AND MAX(t2.TreatedWith) = 'C') 

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Author Comment

by:soozh
ID: 39246932
ok now i understand the "2" is because we have two treatments.
0
 

Author Comment

by:soozh
ID: 39246936
Using chaau's solution i get a syntax error on the line

HAVING COUNT(DISTINCT TreatedWith) = 2

Msg 102, Level 15, State 1, Line 6
Incorrect syntax near '2'.

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Any ideas why?
0
 
LVL 25

Expert Comment

by:chaau
ID: 39247218
I think because your column is defined as nvarchar you need to use N'A' syntax. Can you change it in your database and retest?
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