how to show zero when IN does not return any value sql - sql

Question

I want to return 0 when no rows found for this following condition.
SELECT P.externalid,
Count(DISTINCT Pp.patientuid) patcount
FROM PatientProcedure Pp (nolock )
INNER JOIN visit Temp (nolock )
ON Temp.patientuid = Pp.patientuid
AND (Pp.effectivedate = Temp.VisitDate)
AND Temp.RenderringProviderUid = Pp.serviceprovideruid
AND Temp.VisitDate >= '07-01-2013'
AND Temp.VisitDate <= '06-30-2014'
INNER JOIN serviceprovider Sp (nolock )
ON Pp.serviceprovideruid = Sp.serviceprovideruid
AND Sp.inactive = 0
INNER JOIN MasterCode Mc (nolock )
ON Mc.codeuid = Pp.procedurecodeuid
INNER JOIN MasterCodeSet Mcs (nolock )
ON Mcs.Value = Mc.code
INNER JOIN practice P
ON P.PracticeUid = Temp.practiceuid
WHERE NAME = 'Visual_Field_Exam'
AND Temp.mastervisittypeuid IS NOT NULL
AND P.ExternalID IN ('26900', '26902', '26903', '26906',
'26907', '26908', '26946', '26963',
'27128', '27131', '27133', '27134',
'27135', '27137', '27166', '27167',
'27497', '27498', '27499', '27501',
'27502', '27504', '27505', '27509',
'27510', '27511', '27518')
GROUP BY P.ExternalID
I have found patient count for many practices but no patient found for one practice. So, I want to return count(patientuid) = 0 for that practice.
Here is the sample data.
PracticeId Patcount
26900 2583
26902 826
26903 4085
26906 241
26907 3205
26908 4592
26946 344
26963 398
27128 238
27131 2467
27133 975
27135 815
27137 1252
27166 1038
27167 211
27497 1053
27498 934
27499 3467
27501 617
27502 3511
27504 7222
27505 683
27509 210
27510 1145
27511 181
27518 500
In above output I got data for 26 practices, but "27134" practice does not having patient count, so i want it show 0.
I want above output. How can I achieve it?
Thanks in advance..!

Answer 1

Suppose you have a table Practicer which holds the practicers (i do not know if that is the correct word, but doesn't matter for SQL). Then you need to left join that table with Patient in order to get a list of all Practicers filter by you where clause. So this will get the ones you want.
Select PR.PracticeName,
count(distinct patientid)
from Practicer PR
LEFT JOIN Patient P
ON PR.Practiceid = P.Practiceid
where PR.Practiceid in
('12345','65478','78541')
GROUP BY PR.PracticeName
In general, you want to return 2 fields. The first is the list of Hospitals, Practiotioners or whatever else you may like. In order to get the full list (even if it does not have a count) you need to start with that table.
Lets say we have a table Hospitals that we want to filter on specific ids. The we would have the following query:
SELECT HospitalId,
HospitalName
FROM Hospitals
WHERE HospitalId IN ('26900', '26902', '26903')
Now we would like to know the no of patients in each hospital. We know that hospital with id '26902' has no patients (WOW). If we would go to the Patients table and tried the following:
SELECT HospitalId,
COUNT(*) AS NoOfPatients
FROM Patients
WHERE HospitalId IN ('26900', '26902', '26903')
GROUP BY HospitalId
It would return only ids '26900' and '26903' as the Hospital with id '26902' does not have any patient.
So, how do we figure out the third Hospital?
We join the two tables:
SELECT H.HospitalId,
COUNT(PatienId) AS NoOfPatients
FROM Hospitals H
LEFT JOIN Patients P
WHERE H.HospitalId IN ('26900', '26902', '26903')
GROUP BY H.HospitalId
Now this would return all the requested hospitals with the according number of patients.
Your case is more complex, as we need more joins from the Hospitals to the Patients tables. But i hope my explanation will get you on the right track.
The essence of it is to start from your List Table to your Count table.