根据 Oracle 中对自身的自连接查询更新 table 中的值

Question

我有一个 table，其中包含制造物品的记录事件。我们将每个事件视为具有 2 个状态，这些状态基于同一项目的先前记录事件的详细信息和计算。因此，我开发了一个 SELECT 查询，它使用多个自连接来分析与每个事件相关的先前事件的因素，并计算状态。但是因为这个查询相对较慢，我添加了 2 个状态列，并且我想在事件发生后更新具有计算状态的列。这样我以后就可以在状态列上快速获得报告，而不必每次都运行所有的计算。

这是我的 table:

CREATE TABLE ItemLog
(
   ItemID decimal(11) NOT NULL,
   MessageTime DATE NOT NULL, 
   Temperature float(7), 
   Voltage float(7),
   Status1 VARCHAR2(10 BYTE), 
   Status2 VARCHAR2(10 BYTE),
   CONSTRAINT "ItemLog_PK" PRIMARY KEY ("ItemID ", "MessageTime ")
);

我的 SELECT 计算查询是这样的：

SELECT ItemID, MessageTime, 
    CASE WHEN A.Voltage<B.Voltage and A.Voltage<C.Avg_Voltage and C.SD_Voltage<5 THEN 'Good' ELSE 'Bad' END Calculated_Status1, 
    CASE WHEN A.Temperature<B.Temperature and A.Temperature>C.Temperature and C.SD_Temperature>10 THEN 'Good' ELSE 'Bad' END Calculated_Status2 
FROM ItemLog A,
   (SELECT F.ItemID,
        F.MessageTime Key_MessageTime,
        S.Voltage,
        S.Temperature
    FROM ItemLog F,
        ItemLog S
    WHERE F.ItemID=S.ItemID 
        and S.MessageTime=
            SELECT MAX(MessageTime)
            FROM ItemLog
            WHERE ItemID=F.ItemID
               and MessageTime<F.MessageTime
               and Voltage<12
               and Temperature<125
    ) B,  -- Returns the Voltage and Temperature from the prior time it was <12 and <125
   (SELECT K.ItemID, K.MessageTime,
        AVG(L.Temp) Avg_Temperature, STDDEV(L.Temperature) SD_Temp, 
        AVG(L.Voltage) Avg_Voltage, STDDEV(L.Voltage) SD_Voltage 
    FROM ItemLog K,
        ItemLog L
    WHERE K.ItemID=L.ItemID 
        and L.MessageTime=
            SELECT MAX(MessageTime)
            FROM ItemLog
            WHERE ItemID=K.ItemID
               and MessageTime<K.MessageTime
    GROUP BY K.ItemID, K.MessageTime
     ) C  -- Returns the Voltage and Temperature stats from all prior messages
   (SELECT ItemID 
    FROM ItemLog
    WHERE Voltage>40
     ) D  -- Returns all ItemID where Voltage was ever >40, to exclude them
WHERE A.ItemID=B.ItemID and A.MessageTime=B.MessageTime
  and A.ItemID=C.ItemID and A.MessageTime=C.MessageTime
  and A.ItemID=D.ItemID(+) and D.ItemID IS NULL

所以，问题是，如何将 table 中的 Status1 和 Status2 列更新为 Calculated_Status1 和 Calculated Status2 列？我已尝试采用我的计算查询并通过 2 个主键将其加入 table，但我收到 "ORA-01779: cannot modify a column which maps to a non key-preserved table" 错误。

UPDATE ( 
    SELECT U.*,
        V.Calculated_Status1
        V.Calculated_Status2
    FROM ItemLog U,
        ( <calculation query above> ) V
    WHERE U.ItemID=V.ItemID and U.MessageTime=V.MessageTime )
SET U.Status1=V.CalculatedStatus1,
    U.Status2=V.CalculatedStatus2

我可以想象一个带有 SET Status1=(SELECT... 的 UPDATE，但这需要 ItemID 和 MessageTime 的某种相关 WHERE，我希望它运行非常慢。看起来应该有更直接的方法来做到这一点？

Answer 1

我希望您正在寻找的解决方案可以使用 MERGE 语句提供。我希望您发布的查询是正确的。我已经在查询之上构建了解决方案。如果这有帮助，请告诉我。

MERGE INTO ItemLog it USING
(SELECT ItemID, MessageTime, 
    CASE WHEN A.Voltage<B.Voltage and A.Voltage<C.Avg_Voltage and C.SD_Voltage<5 THEN 'Good' ELSE 'Bad' END Calculated_Status1, 
    CASE WHEN A.Temperature<B.Temperature and A.Temperature>C.Temperature and C.SD_Temperature>10 THEN 'Good' ELSE 'Bad' END Calculated_Status2 
FROM ItemLog A,
   (SELECT F.ItemID,
        F.MessageTime Key_MessageTime,
        S.Voltage,
        S.Temperature
    FROM ItemLog F,
        ItemLog S
    WHERE F.ItemID=S.ItemID 
        and S.MessageTime=
            SELECT MAX(MessageTime)
            FROM ItemLog
            WHERE ItemID=F.ItemID
               and MessageTime<F.MessageTime
               and Voltage<12
               and Temperature<125
    ) B,  -- Returns the Voltage and Temperature from the prior time it was <12 and <125
   (SELECT K.ItemID, K.MessageTime,
        AVG(L.Temp) Avg_Temperature, STDDEV(L.Temperature) SD_Temp, 
        AVG(L.Voltage) Avg_Voltage, STDDEV(L.Voltage) SD_Voltage 
    FROM ItemLog K,
        ItemLog L
    WHERE K.ItemID=L.ItemID 
        and L.MessageTime=
            SELECT MAX(MessageTime)
            FROM ItemLog
            WHERE ItemID=K.ItemID
               and MessageTime<K.MessageTime
    GROUP BY K.ItemID, K.MessageTime
     ) C  -- Returns the Voltage and Temperature stats from all prior messages
   (SELECT ItemID 
    FROM ItemLog
    WHERE Voltage>40
     ) D  -- Returns all ItemID where Voltage was ever >40, to exclude them
WHERE A.ItemID=B.ItemID and A.MessageTime=B.MessageTime
  and A.ItemID=C.ItemID and A.MessageTime=C.MessageTime
  and A.ItemID=D.ItemID(+) and D.ItemID IS NULL)z
ON
(it.ItemID = z.ItemID AND it.MessageTime = z.MessageTime)
WHEN MATCHED THEN
UPDATE SET it.STATUS1 = z.Calculated_Status1,
       it.STATUS2 = z.Calculated_Status2;

根据 Oracle 中对自身的自连接查询更新 table 中的值

Update values in a table based on a self-join query to itself in Oracle

sql

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