SQL Server query using Union - any good alternate possible? - sql-server

Question

I have a SQL Server query as:
SELECT top 1 vConsentInfo FROM
(
SELECT cons.vConsentInfo,cons.dTimeStamp ,logs.iPartnerProfileID
FROM H_OutMessageLog logs INNER JOIN H_OutMessageConsent cons on cons.iOutMessageQID = logs.iOutQueueID
WHERE logs.iPatID = 65686 and logs.iPracID = 4
UNION
SELECT cons.vConsentInfo,cons.dTimeStamp,Q.iPartnerProfileID
FROM H_OutMessageQueue Q INNER JOIN H_OutMessageConsent cons on cons.iOutMessageQID = Q.iOutQueueID
WHERE Q.iPatID = 65686 and Q.iPracID = 4
) A
WHERE A.iPartnerProfileID = Prof.IPartnerProfileID
Order BY dTimeStamp DESC
The table works as : a record get inserted into H_OutMessageQueue at the begining; then its inserted into H_OutMessageConsent...
Now there is a seperate worker process that processes records from H_OutMessageQueue and log them into H_OutMessageLog....
Can I get rid of this UNION thing ? Please note that this is a sub Query of a larger CTE query.

Answer 1

Yes, but it may not be better. You'll have to work this into your bigger query
SELECT TOP 1
cons.vConsentInfo,
ISNULL(logs.iPartnerProfileID , Q.iPartnerProfileID) AS iPartnerProfileID
FROM
H_OutMessageConsent cons
LEFT JOIN
H_OutMessageLog logs ON cons.iOutMessageQID = logs.iOutQueueID AND
logs.iPatID = 65686 and logs.iPracID = 4
LEFT JOIN
H_OutMessageQueue Q ON cons.iOutMessageQID = Q.iOutQueueID AND
Q.iPatID = 65686 and Q.iPracID = 4
WHERE
ISNULL(logs.iPartnerProfileID , Q.iPartnerProfileID) IS NOT NULL
ORDER BY
cons.dTimeStamp DESC

Answer 2

In addition to gbn reply. This will remove the extra burden from your query:).
SELECT top 1 vConsentInfo FROM
(
SELECT cons.vConsentInfo,cons.dTimeStamp ,logs.iPartnerProfileID
From
(
Select iPartnerProfileID FROM H_OutMessageLog logs
WHERE logs.iPatID = 65686 and logs.iPracID = 4
)logs
Left JOIN H_OutMessageConsent cons on cons.iOutMessageQID = logs.iOutQueueID
UNION
SELECT cons.vConsentInfo,cons.dTimeStamp,Q.iPartnerProfileID
From
(
Select iPartnerProfileID FROM H_OutMessageQueue Q
WHERE Q.iPatID = 65686 and Q.iPracID = 4
)Q
Left JOIN H_OutMessageConsent cons on cons.iOutMessageQID = Q.iOutQueueID
) A
WHERE A.iPartnerProfileID = Prof.IPartnerProfileID
Order BY dTimeStamp DESC