Case When Resulting in Null

Question

Case When Resulting in Null

daniness

SSCrazy

Points: 2890
More actions
July 31, 2013 at 10:39 am

#278160

Hi All,
I just need clarification of why a field for some records would result in a null value for a query like the following, particularly for the StatusCd field. I believe it would be when none of the whens apply? Please advise:
SELECT InternalICN
, EncounterLineNum
, STSDate StatusDt
, case HeaderStatus
when 'F0' then 3 -- PAY
when 'VE' then 3
when 'F2' then 4 -- DENY
when 'P2' then 9 -- SUSPEND
when 'PC' then 10
end AS StatusCd
, case HeaderStatus
when 'VE' then 1500
else 600
end AS StatusReasonCd
, isnull(drec.dpwicn,'') as DPWICN
FROM T277.Enc277_2200D drec join
T277.EncounterTrackingTemp et on et.InternalICN = drec.TraceNo
where et.StatusCd <> 2
Thanks!

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Lowell SSC Guru Points: 323504 More actions · Answer 1

you are correct; you are testing for five specific values in your CASE, and there's no explicit ELSE in it to handle other values, and the built in logic structure of the case returns NULL for items that don't match the tests in the CASE when no explicit ELSE is provided.

Lowell

--help us help you! If you post a question, make sure you include a CREATE TABLE... statement and INSERT INTO... statement into that table to give the volunteers here representative data. with your description of the problem, we can provide a tested, verifiable solution to your question! asking the question the right way gets you a tested answer the fastest way possible!

daniness SSCrazy Points: 2890 More actions · Answer 2

Thanks, Lowell. Your response was helpful...I know it's something that may have been obvious, but I just wanted to verify. 🙂

Lowell SSC Guru Points: 323504 More actions · Answer 3

Sanity Checks are always a good thing! glad i could help!

Lowell

--help us help you! If you post a question, make sure you include a CREATE TABLE... statement and INSERT INTO... statement into that table to give the volunteers here representative data. with your description of the problem, we can provide a tested, verifiable solution to your question! asking the question the right way gets you a tested answer the fastest way possible!