Question

我在名为 StockItem 的表上有一个触发器，它触发MSSQL中的表行更新事件。

如果只更新了一行（即一个产品），则触发器似乎有效。

但是，当更新了多行时，我收到以下错误：

Msg 512，Level 16，State 1，Procedure IC_ProductUpdate，Line 7

子查询返回的值超过1。这是不允许的   子查询跟随=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =或当子查询用作   一种表达。声明已经终止。

这是我的触发器：

ALTER TRIGGER [dbo].[IC_ProductUpdate] ON [dbo].[StockItem]
AFTER UPDATE
AS
BEGIN

    -- Get Product Id
    DECLARE @StockItemID INT = (SELECT ItemID FROM INSERTED);

    -- Proceed If This Product Is Syncable
    IF (dbo.IC_CanSyncProduct(@StockItemID) = 1)
    BEGIN

        -- Check If Product Was Synced
        IF ((SELECT COUNT(*) FROM IC_ProductCreateQueue WHERE StockItemID = @StockItemID) > 0)
        BEGIN

            -- Check If Any Important Columns Was Updated
            IF (UPDATE(Weight) OR UPDATE(SpareNumber1))
            BEGIN

                -- Check If There Is A [ProductUpdate] Queue Entry Already Exist For This Product
                IF ((SELECT COUNT(*) FROM IC_ProductUpdateQueue WHERE StockItemID = @StockItemID) > 0)
                BEGIN

                    -- Reset [ProductUpdate] Queue Entry
                    UPDATE IC_ProductUpdateQueue SET Synced = 0
                    WHERE StockItemID = @StockItemID

                END
                ELSE
                BEGIN

                    -- Insert [ProductUpdate] Queue Entry
                    INSERT INTO IC_ProductUpdateQueue (StockItemID, Synced) VALUES
                    (@StockItemID, 0)

                END

            END

        END
        ELSE
        BEGIN

            -- Insert [ProductCreate] Queue Entry
            INSERT INTO IC_ProductCreateQueue (StockItemID, Synced) VALUES
            (@StockItemID, 0);

            -- Insert [ProductUpdate] Queue Entry
            INSERT INTO IC_ProductUpdateQueue (StockItemID, Synced) VALUES
            (@StockItemID, 0);

        END

    END

END

在触发器中处理多行更新的最佳方法是什么？

Answer 1

所以，我认为我已经在整个过程中跟踪了你的逻辑，并将其设置为基础。我已经尝试对这两个部分进行了适当的评论，但是有很多事情要发生，所以请随时让我详细说明某些部分。

基础似乎只有dbo.IC_CanSyncProduct(i.ItemID) = 1受影响的记录才有3个分支：

IC_ProductCreateQueue
中不存在项目

- ＆GT;插入IC_ProductCreateQueue和IC_ProductUpdateQueue
关键字段已更新，该项目同时存在IC_ProductCreateQueue和IC_ProductUpdateQueue

- ＆GT;更新IC_ProductUpdateQueue
关键字段已更新，该项目同时存在IC_ProductCreateQueue但不存在IC_ProductUpdateQueue

- ＆GT;插入IC_ProductUpdateQueue

方案2和方案3由下面的MERGE管理，方案1由insert语句处理。

ALTER TRIGGER [dbo].[IC_ProductUpdate] ON [dbo].[StockItem]
AFTER UPDATE
AS
BEGIN

    -- MERGE ITEMS INTO UPDATE QUEUE WHERE KEY FIELDS WERE UPDATED
    -- AND PRODUCT CAN BE SYNCED AND THE ITEM EXISTS IN THE CREATE QUEUE
    WITH MergeData AS
    (   SELECT  i.ItemID
        FROM    inserted AS i
                INNER JOIN deleted AS d
                    ON d.ItemID = i.ItemID
        WHERE   dbo.IC_CanSyncProduct(i.ItemID) = 1
        AND     (i.SpareNumber1 != d.SpareNumber1 OR i.Weight != d.Weight)
        AND     EXISTS 
                (   SELECT  1 
                    FROM    IC_ProductCreateQueue AS pcq
                    WHERE   pcq.StockItemID = i.ItemID
                )
    )
    MERGE IC_ProductUpdateQueue AS puq
    USING MergeData AS i
        ON i.ItemID = puq.StockItemID
    WHEN MATCHED THEN 
        UPDATE SET Synced = 1
    WHEN NOT MATCHED THEN 
        INSERT (StockItemID, Synced)
        VALUES (i.ItemID, 0);


    -- INSERT INTO BOTH THE UPDATE AND CREATE QUEUES WHERE THE ITEM 
    -- DOES NOT ALREADY EXIST IN THE CREATE QUEUE AND THE PRODUCT
    -- CAN BE SYNCED
    INSERT IC_ProductCreateQueue (StockItemID, Synced)
    OUTPUT inserted.StockItemID, inserted.Synced 
    INTO IC_ProductUpdateQueue (StockItemID, Synced)
    SELECT  i.ItemID, 0
    FROM    inserted AS i
    WHERE   dbo.IC_CanSyncProduct(i.ItemID) = 1
    AND     NOT EXISTS 
            (   SELECT  1 
                FROM    IC_ProductCreateQueue AS pcq
                WHERE   pcq.StockItemID = i.ItemID
            );
END

子查询返回的值超过1 - 我的触发器无法处理多行更新

1 个答案: