CREATE TRIGGER [Purchasing].[uPurchaseOrderDetail] ON [Purchasing].[PurchaseOrderDetail] 
AFTER UPDATE AS 

BEGIN
    DECLARE @Count int;

    SET @Count = @@ROWCOUNT;
    IF @Count = 0 
        RETURN;

    SET NOCOUNT ON;

    BEGIN TRY
        IF UPDATE([ProductID]) OR UPDATE([OrderQty]) OR UPDATE([UnitPrice])
        -- Insert record into TransactionHistory 
        BEGIN
            INSERT INTO [Production].[TransactionHistory]
                ([ProductID]
                ,[ReferenceOrderID]
                ,[ReferenceOrderLineID]
                ,[TransactionType]
                ,[TransactionDate]
                ,[Quantity]
                ,[ActualCost])
            SELECT 
                inserted.[ProductID]
                ,inserted.[PurchaseOrderID]
                ,inserted.[PurchaseOrderDetailID]
                ,'P'
                ,GETDATE()
                ,inserted.[OrderQty]
                ,inserted.[UnitPrice]
            FROM inserted 
                INNER JOIN [Purchasing].[PurchaseOrderDetail] 
                ON inserted.[PurchaseOrderID] = [Purchasing].[PurchaseOrderDetail].[PurchaseOrderID];

            -- Update SubTotal in PurchaseOrderHeader record. Note that this causes the 
            -- PurchaseOrderHeader trigger to fire which will update the RevisionNumber.
            UPDATE [Purchasing].[PurchaseOrderHeader]
            SET [Purchasing].[PurchaseOrderHeader].[SubTotal] = 
                (SELECT SUM([Purchasing].[PurchaseOrderDetail].[LineTotal])
                    FROM [Purchasing].[PurchaseOrderDetail]
                    WHERE [Purchasing].[PurchaseOrderHeader].[PurchaseOrderID] 
                        = [Purchasing].[PurchaseOrderDetail].[PurchaseOrderID])
            WHERE [Purchasing].[PurchaseOrderHeader].[PurchaseOrderID] 
                IN (SELECT inserted.[PurchaseOrderID] FROM inserted);

            UPDATE [Purchasing].[PurchaseOrderDetail]
            SET [Purchasing].[PurchaseOrderDetail].[ModifiedDate] = GETDATE()
            FROM inserted
            WHERE inserted.[PurchaseOrderID] = [Purchasing].[PurchaseOrderDetail].[PurchaseOrderID]
                AND inserted.[PurchaseOrderDetailID] = [Purchasing].[PurchaseOrderDetail].[PurchaseOrderDetailID];
        END;
    END TRY
    BEGIN CATCH
        EXECUTE [dbo].[uspPrintError];

        -- Rollback any active or uncommittable transactions before
        -- inserting information in the ErrorLog
        IF @@TRANCOUNT > 0
        BEGIN
            ROLLBACK TRANSACTION;
        END

        EXECUTE [dbo].[uspLogError];
    END CATCH;
END;