選擇具有最近的日期時間值的記錄

建築

BuildingKey(int) | BuildingID(varchar) | ...

地區

areaKey(int) | areaID(varchar) | buildingKey(int-FK[Buildings]) | ...

交易

transactionKey(int) | areaKey(int-FK[Areas]) | value(float) | trnDateTime(DateTime)

Building中可能有幾個Areas。

所有地區有很多Transactions，不同的value和不同的trnDateTime。

我想要做的就是讓每個Area一個Building（當buildingKey被給予）的最新value（事務）。

我提到了一些以前的問題，例如this one，並試着關注。！

（1）

DECLARE @buildingKey INT 
SET @buildingKey = 3 

;WITH Vals AS (
    SELECT T.areaKey AS AreaKey, 
      T.value AS CurrentValue, 
      T.trnDateTime AS RecordedDateTime,     
      ROW_NUMBER() OVER (PARTITION BY B.buildingKey ORDER BY T.trnDateTime DESC) RowID 

    FROM Buildings B INNER JOIN 
      Areas A ON B.buildingKey = A.buildingKey INNER JOIN 
      Transactions T ON A.areaKey = T.areaKey 

    WHERE B.buildingKey = @buildingKey 
) 
SELECT AreaKey, 
     CurrentValue, 
     MAX(RecordedDateTime) AS RecentReading, 
     RowID 
FROM Vals 
WHERE RowID = 1 
GROUP BY AreaKey, CurrentValue, RowID

）返回的最新值（所有領域中）; 不是最新值各地區！！

（2）

DECLARE @buildingKey INT 
SET @buildingKey = 3 

SELECT A.areaKey AS AreaKey, 
     A.areaID AS AreaID, 
     T.value AS CurrentValue, 
     T.trnDateTime AS RecordedDateTime     

FROM Areas A, Buildings B, Transactions T 

WHERE @buildingKey = B.buildingKey AND 
     B.buildingKey = A.buildingKey AND 
     T.areaKey = A.areaKey AND 
     T.trnDateTime IN (SELECT MAX(T.trnDateTime), T.areaKey 
            FROM Transactions T 
            GROUP BY T.areaKey)

）給出了一個錯誤 - >

Msg 116, Level 16, State 1, Line 16 
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

來源

2013-02-05 CRoshanLG

編輯這兩個查詢我都試過了，根據我在上面已經給出了表格的說明。（讓他們更容易理解，更通用） – CRoshanLG

嘗試

DECLARE @buildingKey INT 
SET @buildingKey = 3 

SELECT A.areaKey AS AreaKey, 
     A.areaID AS AreaID, 
     T.value AS CurrentValue, 
     T.trnDateTime AS RecordedDateTime 

FROM Areas A, Buildings B, Transactions T 

WHERE @buildingKey = B.buildingKey AND 
     B.buildingKey = A.buildingKey AND 
     T.areaKey = A.areaKey AND 
     T.trnDateTime IN (SELECT MAX(T.trnDateTime) 
            FROM Transactions T 
            GROUP BY T.areaKey)

來源

2013-02-05 08:30:00 Aditi

完美工作！謝謝你... 我編輯了你的答案，以匹配問題頂部由我給出的表格定義。（我編輯了我也試過的東西。）希望這會使問題更加通用，並且易於理解。 – CRoshanLG

這會給你的每一個建築面積最新的。

(PARTITION BY B.BuildingKey, a.areaKey ORDER BY T.TransactionDateTime DESC) RowID

來源

2013-02-05 08:28:36

SELECT A.areaKey AS AreaKey, 
     A.areaID AS AreaID, 
     T.value AS CurrentValue, 
     T.trnDateTime AS RecordedDateTime     
FROM Areas A JOIN Buildings B ON B.buildingKey = A.buildingKey 
      JOIN Transactions T ON T.areaKey = A.areaKey 
WHERE @buildingKey = B.buildingKey AND EXISTS (
             SELECT 1 
             FROM Transactions T2 
             WHERE T.areaKey = T2.areaKey 
             GROUP BY T2.areaKey 
             HAVING MAX(T2.trnDateTime) = T.trnDateTime 
               )

來源

2013-02-05 09:20:26

工作正常！ Upvoted！ – CRoshanLG

選擇具有最近的日期時間值的記錄

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