Question

我有一个历史记录表（如日志），记录部分的更改：

TransactionID    Part ID          Description        Last Updated
1                1                Fixed O-ring       2006-03-14 20:00:04.700
2                2                Replaced coil      2009-01-02 20:00:04.700
3                1                Replaced coil      2009-01-02 20:00:04.700
4                1                Replaced LED       2002-08-20 20:00:04.700      
5                2                Sealed leakage     2007-03-08 20:00:04.700   
6                3                Replace connector  2004-05-16 20:00:04.700

我有另一张表格，会显示每个部分ID代表什么，但这不是我现在面临的问题。我需要编写一个查询，返回对每个部分进行的最新维护。所以在这种情况下，我的预期输出将是：

TransactionID    Part ID          Description        Last Updated
2                2                Replaced coil      2009-01-02 20:00:04.700    
3                1                Replaced coil      2009-01-02 20:00:04.700 
6                3                Replace connector  2004-05-16 20:00:04.700

说明：例如，部件ID＃1的最新维护工作已于2009-01-02 20：00：04.700完成，依此类推。

我已经尝试了SELECT DISTINCT，但它不会起作用，因为基本上每一行都会有所不同。我完全没有线索。如果我使用MAX(Last Updated)，它将只返回整个表的一行。

已编辑：无论如何，我不允许使用动态查询。

Answer 1

SELECT TransactionID
      ,PartID
      ,[Description]
      ,[Last Updated]
FROM (
    SELECT TransactionID
          ,PartID
          ,[Description]
          ,[Last Updated]
          ,ROW_NUMBER() OVER (PARTITION BY [PartID] ORDER BY [Last Updated] DESC) RN 
    FROM TableName
    )A
WHERE A.RN = 1

或者您可以使用CTE

;WITH CTE AS
  (
    SELECT TransactionID
          ,PartID
          ,[Description]
          ,[Last Updated]
          ,ROW_NUMBER() OVER (PARTITION BY [PartID] ORDER BY [Last Updated] DESC) RN 
    FROM TableName
  )
SELECT TransactionID
      ,PartID
      ,[Description]
      ,[Last Updated]  
FROM CTE 
WHERE A.RN = 1

Answer 2

select 
    TransactionID, PartID, Description, LastUpdated
from 
    History H
where
    LastUpdated = 
    (
        select 
            max(LastUpdated) 
        from 
            History
        where
            PartID = H.PartID
    )

Answer 3

这是我怎么做的

 ;WITH CTE AS 
 (
 Select PartId, MAX(LASTUPDATED) as 'MAXX' from part group by PartId
 ) 
 Select TransActionId, p.PartId, Description, p.LASTUPDATED
 from Part p
 inner join CTE on p.LastUpdated = CTE.MAXX
                and p.PartId = CTE.PartId

Answer 4

SELECT t.TransactionID, t.PartID, t.Description, t.LastUpdated
FROM History t
JOIN (SELECT PartID, MAX(TransactionID)
FROM History
GROUP BY PartID) t2 ON t.PartID = t2.PartID
AND t.TransactionID = t2.TransactionID

也可以。

获取每条记录的最新日期

4 个答案: