1

我有三张桌子

建筑物

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

领域

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

交易

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


Areas一个中 可能有几个Building。

各个领域都有很多Transactions，value各有千秋trnDateTime。

我想要做的是获取每个a的最新value（事务）（当给出时）。 AreaBuildingbuildingKey

我提到了一些以前的问题，比如这个，并尝试了以下问题。

(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

!) 返回最新值（在所有区域中）；不是每个区域的最新值！

(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)

!) 给出一个错误 -->

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.
4

3 回答 3

2

这将为您提供每栋建筑的最新区域。

(PARTITION BY B.BuildingKey, a.areaKey ORDER BY T.TransactionDateTime DESC) RowID
于 2013-02-05T08:28:36.383 回答
2 
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
                                               )
于 2013-02-05T09:20:26.057 回答
1

尝试

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)
于 2013-02-05T08:30:00.363 回答