触发导致子查询返回超过 1 个值

Question

我很少使用触发器，但在更新语句上执行触发器时我似乎遇到了问题。例如，我有一个名为 Project 的表，我们允许软删除。我所说的软删除是在这个表中我们有一个名为Deleted的位字段，如果为真则表示记录已被删除，如果为假则表示它是有效记录。

现在这个表有很多关系（引用这个项目的表）。例如，一个项目可以有多个与之关联的程序。所以我有一个ProgramProject 表，其中一个程序可以有多个项目（1 对多关系，其中 1 是程序，许多是项目）。所以当我删除一个项目时（根据我上面提到的），触发器应该删除与之关联的所有项目......

但是，在某些情况下，当触发器执行时，它似乎会返回错误：

System.Data.SqlClient.SqlException was caught HResult=-2146232060 Message=Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

我是否错误地执行了这些触发器？下面是一个触发器的例子：

ALTER TRIGGER [dbo].[trDeleteProject] ON [dbo].[Project]
FOR UPDATE
AS 
BEGIN
    SET NOCOUNT ON;

    --check if the Deleted field was updated
    IF(UPDATE(Deleted))
        BEGIN
            DECLARE @WasDeleted bit
            DECLARE @ProjectID int

            --get the project that was just deleted
            SET @ProjectID = (SELECT ProjectID FROM Inserted)
            --get whether they want the record deleted (1) or not (0)
            SET @WasDeleted = (SELECT Deleted FROM Inserted)

            --did they want to delete it? (1)
            if (@WasDeleted=1)
                BEGIN
                --yes they delete the record so we remove instances...

                    --1.)Remove programs when a project is deleted
                    UPDATE ProgramProject SET Deleted=1 WHERE ProjectID = @ProjectID

                    --2.)Remove project contact roles when you delete a project
                    UPDATE ProjectContactRole SET Deleted=1 WHERE ProjectID = @ProjectID

                    --3.)Remove sub projects when you delete a project
                    --UPDATE SubProject SET Deleted=1 WHERE ProjectID = @ProjectID

                    --4.)Remove any transport system when you delete a project
                    UPDATE ProjectTransportSystem SET Deleted=1 WHERE ProjectID = @ProjectID

                    --5.)Remove any project mechanical architecture when you delete a project
                    UPDATE ProjectMechanicalArchitecture SET Deleted=1 WHERE ProjectID = @ProjectID

                    --6.)Remove any install personnel when you delete a project
                    UPDATE ProjectInstallPersonnel SET Deleted=1 WHERE ProjectID = @ProjectID
                     END
        END
END

我是否因为它是触发器而错误地执行此操作？我应该加入某个临时表而不是单个更新语句吗？

更新

我尝试使用 M Ali 的示例，但遇到了同样的问题，子查询返回超过 1 行...

这是我使用的代码：

ALTER TRIGGER [dbo].[trDeleteProject] ON [dbo].[Project]
FOR UPDATE
AS 
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    SELECT * INTO #temp 
    FROM Inserted i
    WHERE i.deleted = 1

        --1.)Remove programs when a project is deleted
        UPDATE P 
        SET p.Deleted = 1 
        FROM #temp t INNER JOIN ProgramProject p ON P.ProjectID = t.ProjectID

        --2.)Remove project contact roles when you delete a project
        UPDATE Pr 
        SET pr.Deleted = 1 
        FROM #temp t INNER JOIN ProjectContactRole pr ON Pr.ProjectID = t.ProjectID

        --3.)Remove sub projects when you delete a project
        UPDATE SP 
        SET SP.Deleted = 1 
        FROM #temp t INNER JOIN SubProject sp ON SP.ProjectID = t.ProjectID

        --4.)Remove any transport system when you delete a project
        UPDATE PTS 
        SET PTS.Deleted = 1 
        FROM #temp t INNER JOIN ProjectTransportSystem PTS ON PTS.ProjectID = t.ProjectID

        --5.)Remove any project mechanical architecture when you delete a project
        UPDATE PMA 
        SET PMA.Deleted = 1 
        FROM #temp t INNER JOIN ProjectMechanicalArchitecture PMA ON PMA.ProjectID = t.ProjectID

        --6.)Remove any install personnel when you delete a project
        UPDATE PIP 
        SET PIP.Deleted = 1 
        FROM #temp t INNER JOIN ProjectInstallPersonnel PIP ON PIP.ProjectID = t.ProjectID

        --7.)Remove any install shifts when you delete a project
        UPDATE PIS
        SET PIS.Deleted = 1
        FROM #temp t INNER JOIN ProjectInstallShift PIS ON PIS.ProjectID = t.ProjectID

        --8.)Remove any install windows when you delete a project
        UPDATE PIW
        SET PIW.Deleted = 1
        FROM #temp t INNER JOIN ProjectInstallWindow PIW ON PIW.ProjectID = t.ProjectID

        --9.)Remove any project pallet type when you delete a project
        UPDATE PPT
        SET PPT.Deleted = 1
        FROM #temp t INNER JOIN ProjectPalletType PPT ON PPT.ProjectID = t.ProjectID

        --10.)Remove issues related to a project
        UPDATE I
        SET I.Deleted = 1
        FROM #temp t INNER JOIN Issue I ON I.ProjectID = t.ProjectID

        --11.)Remove measurement architecture for a project
        UPDATE PMAS
        SET PMAS.Deleted = 1
        FROM #temp t INNER JOIN ProjectMeasurementArchitectureSystem PMAS ON PMAS.ProjectID = t.ProjectID

        --12.)Remove controls architecture for a project
        UPDATE PCAS
        SET PCAS.Deleted = 1
        FROM #temp t INNER JOIN ProjectControlsArchitectureSystem PCAS ON PCAS.ProjectID = t.ProjectID                  
END

Answer 1

只需将逻辑删除的行放入临时表中，然后将该临时表与每个相关表连接起来，然后更新它们表中的已删除字段。

您可以简单地使用已删除的表本身与您要更新的每个表连接，但仅在字段已删除 = 1 限制临时表中的行数或行的情况下将行插入临时表。加入一个相对较小的表会给你一些性能提升。请看下面：

ALTER TRIGGER [dbo].[trDeleteProject] ON [dbo].[Project]
FOR UPDATE
AS 
BEGIN
    SET NOCOUNT ON;
-- Get logically deleted rows into a temp table 

 SELECT * INTO #temp 
 FROM Inserted i
 WHERE i.deleted = 1

        --1.)Remove programs when a project is deleted
        UPDATE P 
        SET p.Deleted = 1 
        FROM #temp t INNER JOIN ProgramProject p ON P.ProjectID = t.ProjectID

        --2.)Remove project contact roles when you delete a project
        UPDATE Pr 
        SET pr.Deleted = 1 
        FROM #temp t INNER JOIN ProjectContactRole pr ON Pr.ProjectID = t.ProjectID

        --3.)Remove sub projects when you delete a project
        UPDATE SP 
        SET SP.Deleted = 1 
        FROM #temp t INNER JOIN SubProject sp ON SP.ProjectID = t.ProjectID

        --4.)Remove any transport system when you delete a project
        UPDATE PTS 
        SET PTS.Deleted = 1 
        FROM #temp t INNER JOIN ProjectTransportSystem PTS ON PTS.ProjectID = t.ProjectID

        --5.)Remove any project mechanical architecture when you delete a project
        UPDATE PMA 
        SET PMA.Deleted = 1 
        FROM #temp t INNER JOIN ProjectMechanicalArchitecture PMA ON PMA.ProjectID = t.ProjectID

        --6.)Remove any install personnel when you delete a project
        UPDATE PIP 
        SET PIP.Deleted = 1 
        FROM #temp t INNER JOIN ProjectInstallPersonnel PIP ON PIP.ProjectID = t.ProjectID

END

更新

既然您提到您希望一次使用一个 projectID 更新表格。要实现这一点，您需要再次创建一个 while 循环和一个临时表，并循环遍历您的临时表以按 projectid 更新每个表 projectid 中的记录，我真的认为这对于一个相当简单的任务来说是一种过度杀伤力。见下文：

ALTER TRIGGER [dbo].[trDeleteProject] ON [dbo].[Project]
FOR UPDATE
AS 
BEGIN
    SET NOCOUNT ON;

--check if the Deleted field was updated
    DECLARE @ProjectID int

  SELECT * INTO #Temp 
  FROM Inserted 
  WHERE deleted = 1

    --did they want to delete it? (1)
    WHILE EXISTS (SELECT * FROM #Temp)
        BEGIN
              SELECT TOP 1 @ProjectID = ProjectID 
              FROM #Temp

            --1.)Remove programs when a project is deleted
            UPDATE ProgramProject SET Deleted=1 WHERE ProjectID = @ProjectID

            --2.)Remove project contact roles when you delete a project
            UPDATE ProjectContactRole SET Deleted=1 WHERE ProjectID = @ProjectID

            --3.)Remove sub projects when you delete a project
            --UPDATE SubProject SET Deleted=1 WHERE ProjectID = @ProjectID

            --4.)Remove any transport system when you delete a project
            UPDATE ProjectTransportSystem SET Deleted=1 WHERE ProjectID = @ProjectID

            --5.)Remove any project mechanical architecture when you delete a project
            UPDATE ProjectMechanicalArchitecture SET Deleted=1 WHERE ProjectID = @ProjectID

            --6.)Remove any install personnel when you delete a project
            UPDATE ProjectInstallPersonnel SET Deleted=1 WHERE ProjectID = @ProjectID

         DELETE FROM #Temp WHERE ProjectID = @ProjectID  

       END 
END