Question

我有一个SQL Server查询：

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

该表的作用如下：记录在开始时插入H_OutMessageQueue;然后将其插入H_OutMessageConsent ... 现在有一个单独的工作进程处理来自H_OutMessageQueue的记录并将其记录到H_OutMessageLog ....

我可以摆脱这个UNION的事吗？请注意，这是较大CTE查询的子查询。

Answer 1

是的，但可能更好。您必须将其用于更大的查询

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

除了gbn回复。这将消除查询中的额外负担:)。

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

使用Union的SQL Server查询 - 任何好的备用可能吗？

2 个答案: