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Delete unwanted rows

Posted on 2013-06-15
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Last Modified: 2013-07-01
I have a table "TreatmentData" defined as:

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

The table lists patient treatments.  A patient can have many rows in the table.  There are six possible values for TreatedWith.

I need to delete all the patient records where the patient has "NoTreatment" for all his/her rows in the database.  i.e. they have visited the clinic but not been treated.

I imagine it must be where the number of rows is equal to the count where the TreatedWith is "NoTreatment" when grouped by PatientId...

but i just can not get my head round it.

Any suggestions?
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Question by:soozh
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5 Comments
 
LVL 16

Assisted Solution

by:Surendra Nath
Surendra Nath earned 1000 total points
ID: 39250522
the below query might help you out

;with CTE as
(
 select PatientId,TreatedWith  from #TreatmentData group by PatientId,TreatedWith 
), CTE1 AS
(
 select PatiendID from CTE C WHERE NOT EXISTS ( select 1 FROM CTE C1 where C1.PatiendID = C.PatiendID and C1.TreatedWith  <> 'NoTreatment')
)
DELETE T
FROM #TreatmentData T
JOIN CTE1 C
ON T.PatiendID = C.PatiendID

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0
 
LVL 5

Expert Comment

by:DOSLover
ID: 39250869
Essentially what we are saying here is that delete the patient record if we find only 'NoTreatment' records for that patient:
Delete from TreatmentData a
 where exists 
       (Select PatientId from TreatmentData b
	     where b.PatientId = a.PatientId
		   and b.TreatedWith = 'NoTreatment')
   and NOT exists 
       (Select PatientId from TreatmentData b
	     where b.PatientId = a.PatientId
		   and b.TreatedWith <> 'NoTreatment')

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0
 
LVL 32

Accepted Solution

by:
Ephraim Wangoya earned 1000 total points
ID: 39251119
Here

with cte as
(
  select *
  from TreatmentData
  where TreatedWith <> 'NoTreatment'
)

delete from TreatMentData
where not exists(select 1 
                           from cte A
                           where TreatmentData.PatientID = A.PatientID)

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0
 
LVL 25

Expert Comment

by:chaau
ID: 39252003
Just kidding: when you apply all the SQL statements against you treatment table that you have asked during last week, you will probably end up with a nice empty table. Ha-ha
0
 
LVL 32

Expert Comment

by:awking00
ID: 39253464
delete from treatmentdata
where patientid in
(select patientid from treatmentdata where treatedwith = 'NoTreatment'
 except
 select patientid from treatmentdata where treatedwith <> 'NoTreatment')
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