SQL消除與馬克斯日期dupliates

Question

我有以下查詢：

(
Select Event.EventID, Event_Reps.LastName , Event_reps.FirstName, Cost.EventDate 
From Cost WITH(NOLOCK) 
inner join Event WITH(NOLOCK) on Cost.EventID = Event.EventID 
inner join Event_Reps WITH(NOLOCK) on Cost.EventRep = Event_Reps.EventRep 
where Event.EventID = 66 
and Event_Reps.Division = 'Houston' and Cost.CostAmt = 0 
) as table1 

由於有在一個給定的事件ID的成本表重複的記錄，我需要找到具有最大的EVENTDATE一個。 我不知道如何更改上述查詢，以便它做它做的事情，但消除了重複項並給我具有最大EventDate的成本記錄。

Answer 1

有很多方法可以爲一隻貓皮膚...測試每一種方法以找出哪種方法在桌子設計和RDBMS方面表現更好。我相當肯定我也錯過了一些出路。

帶窗口的功能

SELECT * 
FROM ( SELECT Event.EventID, 
        Event_Reps.LastName , 
        Event_reps.FirstName, 
        Cost.EventDate, 
        MAX(Cost.EventDate) OVER(PARTITION BY EventID) [MaxEventDate] 
      FROM Cost WITH(NOLOCK) 
        INNER JOIN Event WITH(NOLOCK) 
         ON Cost.EventID = Event.EventID 
        INNER JOIN Event_Reps WITH(NOLOCK) 
         ON Cost.EventRep = Event_Reps.EventRep 
      WHERE Event.EventID = 66 
      AND  Event_Reps.Division = 'Houston' 
      AND  Cost.CostAmt = 0 
     ) as table1 
WHERE MaxEventDate = EventDate 

OR

SELECT * 
FROM ( SELECT Event.EventID, 
        Event_Reps.LastName , 
        Event_reps.FirstName, 
        Cost.EventDate, 
        ROW_NUMBER() OVER(PARTITION BY EventID ORDER BY Cost.EventID) [RowNumber] 
      FROM Cost WITH(NOLOCK) 
        INNER JOIN Event WITH(NOLOCK) 
         ON Cost.EventID = Event.EventID 
        INNER JOIN Event_Reps WITH(NOLOCK) 
         ON Cost.EventRep = Event_Reps.EventRep 
      WHERE Event.EventID = 66 
      AND  Event_Reps.Division = 'Houston' 
      AND  Cost.CostAmt = 0 
     ) as table1 
WHERE RowNumber = 1 

或聚集

SELECT * 
FROM ( SELECT Event.EventID, 
        Event_Reps.LastName , 
        Event_reps.FirstName, 
        Cost.EventDate, 
        ROW_NUMBER() OVER(PARTITION BY EventID ORDER BY Cost.EventID) [RowNumber] 
      FROM Cost WITH(NOLOCK) 
        INNER JOIN Event WITH(NOLOCK) 
         ON Cost.EventID = Event.EventID 
        INNER JOIN Event_Reps WITH(NOLOCK) 
         ON Cost.EventRep = Event_Reps.EventRep 
        INNER JOIN 
        ( SELECT EventID, MAX(EventDate) [EventDate] 
         FROM Cost 
         GROUP BY EventID 
        ) MaxCost 
         ON MaxCost.EventID = Cost.EventID 
         AND MaxCost.EventDate = Cost.EventDate 
      WHERE Event.EventID = 66 
      AND  Event_Reps.Division = 'Houston' 
      AND  Cost.CostAmt = 0 
     ) as table1 

或連接的

SELECT * 
FROM ( SELECT Event.EventID, 
        Event_Reps.LastName , 
        Event_reps.FirstName, 
        Cost.EventDate, 
        ROW_NUMBER() OVER(PARTITION BY EventID ORDER BY Cost.EventID) [RowNumber] 
      FROM Cost WITH(NOLOCK) 
        INNER JOIN Event WITH(NOLOCK) 
         ON Cost.EventID = Event.EventID 
        INNER JOIN Event_Reps WITH(NOLOCK) 
         ON Cost.EventRep = Event_Reps.EventRep 
        LEFT JOIN Cost c2 
         ON c2.EventID = Cost.EventID 
         AND c2.EventDate > Cost.EventDate 
      WHERE Event.EventID = 66 
      AND  Event_Reps.Division = 'Houston' 
      AND  Cost.CostAmt = 0 
      AND  Cost.EventID IS NULL 
     ) as table1 

或者雖然存在

SELECT * 
FROM ( SELECT Event.EventID, 
        Event_Reps.LastName , 
        Event_reps.FirstName, 
        Cost.EventDate, 
        ROW_NUMBER() OVER(PARTITION BY EventID ORDER BY Cost.EventID) [RowNumber] 
      FROM Cost WITH(NOLOCK) 
        INNER JOIN Event WITH(NOLOCK) 
         ON Cost.EventID = Event.EventID 
        INNER JOIN Event_Reps WITH(NOLOCK) 
         ON Cost.EventRep = Event_Reps.EventRep 
      WHERE Event.EventID = 66 
      AND  Event_Reps.Division = 'Houston' 
      AND  Cost.CostAmt = 0 
      AND  NOT EXISTS 
        ( SELECT 1 
         FROM Cost c2 
         WHERE c2.EventID = Cost.EventID 
         AND  c2.EventDate > Cost.EventDate 
        ) 
     ) as table1 

您正在使用什麼版本的SQL