SQL Server：INSTEAD OF UPDATE 触发器：动态代码生成；插入的表不可用

Question

我有一个INSTEAD OF UPDATE 触发器，它动态生成代码然后执行它。问题是当代码执行时我总是得到错误信息：

无效的对象名称“插入”

触发代码是这样的：

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER Trigger [dbo].[TACMasterLayouts_VersionVisibilityHandling_updates] 
ON [dbo].[TACMasterLayouts_VersionVisibilityHandling] 
INSTEAD OF UPDATE
AS
    IF @@rowcount = 0 
        RETURN; 

    SET NOCOUNT ON

    DECLARE @tableToUpdate AS NVARCHAR(MAX) = 'dbo.tacmasterlayouts';
    DECLARE @UpdateStatement AS NVARCHAR(MAX) 
    DECLARE @IdentityField AS NVARCHAR(MAX) = (SELECT Name 
                                               FROM sys.columns 
                                               WHERE [object_id] = OBJECT_ID('dbo.tacmasterlayouts') 
                                                  AND is_identity = 1)

    SET @UpdateStatement = 'update ' + @tableToUpdate + ' set ';

    DECLARE @Fields AS NVARCHAR(MAX)

    SELECT @Fields = COALESCE(@Fields + ', ', '') + @tableToUpdate + '.' + Name + ' = inserted.' + Name 
    FROM sys.columns 
    WHERE [object_id] = OBJECT_ID('dbo.tacmasterlayouts') 
      AND Name != @IdentityField;

    SET @UpdateStatement = @UpdateStatement + @fields

    SET @UpdateStatement = @UpdateStatement + ' FROM ' + @tableToUpdate + ', inserted'
    SET @UpdateStatement = @UpdateStatement + ' where ' + @tableToUpdate + '.' + @IdentityField + ' = inserted.' + @IdentityField

    EXECUTE sp_executesql @UpdateStatement

动态代码如下：

UPDATE TACMasterLayouts SET

 TACMasterLayouts.TACMasterLayoutName = inserted.TACMasterLayoutName, 
 TACMasterLayouts.TACMasterLayoutDestinationFileName = inserted.TACMasterLayoutDestinationFileName, 
 TACMasterLayouts.LayoutTypeCategoryId = inserted.LayoutTypeCategoryId, 
 TACMasterLayouts.LayoutTypeId = inserted.LayoutTypeId, 
 TACMasterLayouts.TACMasterLayoutDescription = inserted.TACMasterLayoutDescription, 
 TACMasterLayouts.TACMasterLayoutJasper = inserted.TACMasterLayoutJasper, 
 TACMasterLayouts.TACMasterLayoutJrxml = inserted.TACMasterLayoutJrxml, 
 TACMasterLayouts.TACMasterLayoutHtml = inserted.TACMasterLayoutHtml, 
 TACMasterLayouts.TACMasterLayoutDontClone = inserted.TACMasterLayoutDontClone, 
 TACMasterLayouts.TACMasterLayoutIsSubReport = inserted.TACMasterLayoutIsSubReport, 
 TACMasterLayouts.TACMasterLayoutVersion = inserted.TACMasterLayoutVersion, 
 TACMasterLayouts.TACMasterLayoutKey = inserted.TACMasterLayoutKey, 
 TACMasterLayouts.TACMasterLayoutTimestampLastModified = inserted.TACMasterLayoutTimestampLastModified, 
 TACMasterLayouts.TACMasterLayoutHash = inserted.TACMasterLayoutHash, 
 TACMasterLayouts.TACMasterLayoutTimestampLastCheckout = inserted.TACMasterLayoutTimestampLastCheckout,
 TACMasterLayouts.TACMasterLayoutCheckedOutByUserId = inserted.TACMasterLayoutCheckedOutByUserId,
 TACMasterLayouts.TACMasterLayoutIsCheckedIn = inserted.TACMasterLayoutIsCheckedIn, 
 TACMasterLayouts.TACMasterLayoutCheckedInByUserId = inserted.TACMasterLayoutCheckedInByUserId, 
 TACMasterLayouts.TACMasterLayoutCheckedOutFolderName = inserted.TACMasterLayoutCheckedOutFolderName 

FROM TACMasterLayouts, inserted
WHERE TACMAsterlayouts.TACMasterLayoutId = inserted.TACMasterLayoutId;

提示：

如果我在触发器中静态输入动态生成的代码，它可以正常工作。所以代码本身没问题。

问题：为什么inserted 在这种情况下不可用？以及如何解决？

Answer 1

根据我的发现，您似乎无法以这种方式在动态 SQL 中使用 inserted 表，但您应该能够使用SQLCLR

Using the inserted / deleted tables in Dynamic SQL

Answer 2

执行动态 sql 时，它有自己的范围，就像调用另一个存储过程一样，因此它不能引用触发器范围内的内容，例如插入、删除或局部变量等。您必须在所需键值的动态 sql 字符串，并准备处理多于 1 行的插入导致触发器触发。

Answer 3

由于上述答案没有给我想要的解决方案，我进一步挖掘并找到了以下 - 酷 - 解决方案（感谢以下文章：https://www.sqlteam.com/forums/topic.asp?TOPIC_ID=11318）：

如果您需要将插入的表传递给动态 SQL 代码（传递给 sp_executesql 存储过程），请执行以下操作：

select * from inserted into #inserted

然后您可以立即在#inserted 下的sp_executesql 中访问它。无需将此作为参数传递给 sp_executesql。

最终的工作代码如下所示：

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER Trigger [dbo].[TACMasterLayouts_VersionVisibilityHandling_updates] on [dbo].[TACMasterLayouts_VersionVisibilityHandling] INSTEAD OF update  
as 
 if @@rowcount = 0 return; 
 SET NOCOUNT ON

 Declare @tableToUpdate AS Nvarchar(max) = 'dbo.tacmasterlayouts';
 Declare @UpdateStatement AS Nvarchar(max)
 Declare @IdentityField as Nvarchar(max) = (SELECT Name FROM sys.columns WHERE [object_id] = OBJECT_ID(@tableToUpdate) and is_identity = 1)

 set @UpdateStatement = 'update ' + @tableToUpdate + ' set ';

 Declare @Fields AS Nvarchar(MAX)
 SELECT  @Fields = COALESCE(@Fields + ', ', '') + @tableToUpdate + '.' + Name + ' = #inserted.' + Name FROM sys.columns WHERE [object_id] = OBJECT_ID(@tableToUpdate) and Name != @IdentityField;

 set @UpdateStatement = @UpdateStatement + @fields

 set @UpdateStatement = @UpdateStatement + ' FROM ' + @tableToUpdate + ', #inserted'
 set @UpdateStatement = @UpdateStatement + ' where ' + @tableToUpdate + '.' + @IdentityField + ' = #inserted.' + @IdentityField

 select * into #inserted from inserted 

 EXECUTE sp_executesql @UpdateStatement