Question

我想知道是否有更有效的方法来进行以下查询。

const store = createStore(rootReducer, {}, applyMiddleware(thunk));

我担心构建I_POSN_DIM列的查询。查询的执行速度很慢，似乎必须反复扫描该查询以提取结果。这是在postgresql中，我对这个平台不那么熟悉。我尝试使用使用MAX函数的CTE，但COUNT始终与此查询不同。任何帮助都会得到补偿。

Answer 1

我认为是这样的：

SELECT 
t.iCertification_UserCertificationTranscriptID  AS I_CERT_TRANSCRIPT_DIM, 
t.iHR_UserID                                    AS I_EMP_DIM, 
t.iCertification_CertificationID                AS I_RUL_CERT_DIM,
uPG.iHR_PositionID                              AS I_POSN_DIM,                                    
(t.dEffectiveStart.Year * 10000 + t.dEffectiveStart.Month * 100 +  t.dEffectiveStart.Day)   AS I_DAY_STRT_DIM, 
(t.dEffectiveEnd.Year * 10000 + t.dEffectiveEnd.Month * 100 + t.dEffectiveEnd.Day)         AS I_DAY_END_DIM,  
CASE WHEN t.iCertification_TranscriptSourceID = '1' THEN 'Y' ELSE 'N' END                                                                       AS L_AdminOverride,
t.mComment                                      AS X_Comment
FROM dbo.tCertification_UCT AS t
INNER JOIN UserProfileNoGroups uPG ON t.iHR_UserID = uPG.iHR_UserID
WHERE Profile_IsPrimary = '1'
        AND UserPosition_IsPrimary = '1'
        AND (t.dEffectiveStart BETWEEN UserPosition_Effective AND COALESCE(UserPosition_End, LOCALTIMESTAMP));

我将内部查询移到外部，并在等效的内部联接中将其转换。在其他字段中，您确实进行过强制转换，但这不是必需的，因为该操作的结果是一个整数。

但是我认为表UserProfileNoGroups在tCertification_UCT的每个记录都有1条记录。如果不是这样，查询将更改一个小标题：

SELECT 
t.iCertification_UserCertificationTranscriptID  AS I_CERT_TRANSCRIPT_DIM, 
t.iHR_UserID                                    AS I_EMP_DIM, 
t.iCertification_CertificationID                AS I_RUL_CERT_DIM,
uPG.iHR_PositionID  OVER (ORDER BY UserPosition_Effective DESC)                         AS I_POSN_DIM,                                    
(t.dEffectiveStart.Year * 10000 + t.dEffectiveStart.Month * 100 +  t.dEffectiveStart.Day)   AS I_DAY_STRT_DIM, 
(t.dEffectiveEnd.Year * 10000 + t.dEffectiveEnd.Month * 100 + t.dEffectiveEnd.Day)         AS I_DAY_END_DIM,  
CASE WHEN t.iCertification_TranscriptSourceID = '1' THEN 'Y' ELSE 'N' END                              AS L_AdminOverride,
t.mComment                                      AS X_Comment
FROM dbo.tCertification_UCT AS t
INNER JOIN UserProfileNoGroups uPG ON t.iHR_UserID = uPG.iHR_UserID
WHERE Profile_IsPrimary = '1'
        AND UserPosition_IsPrimary = '1'
        AND (t.dEffectiveStart BETWEEN UserPosition_Effective AND COALESCE(UserPosition_End, LOCALTIMESTAMP));

您可以使用OVER子句：

https://www.postgresql.org/docs/9.1/tutorial-window.html

子查询建立列

1 个答案: