Question

我创建触发器的经验有限。这是我最近创建的一个：

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER TRIGGER [dbo].[NameTrigger]
ON [dbo].[dbUSNs]
after INSERT, UPDATE
AS 
BEGIN
    SET NOCOUNT ON;
    declare @URNs varchar(100)
    declare @Forenames varchar(200)
    declare @Surname varchar(100)
    declare @Reference int

    set @URNs = ''
    set @Forenames = ''
    set @Surname = ''
    set @Reference = 0

    declare PersonCursor cursor FOR   
    select 
    Replace(Replace(Replace(Forenames,char(39),''),'-',''),' ',''),
    Replace(Replace(Replace(Surname,char(39),''),'-',''),' ',''),
    Reference,USN from inserted
    open PersonCursor

    FETCH NEXT FROM PersonCursor INTO @Forenames, @Surname, @Reference, @URNs
                WHILE @@FETCH_STATUS = 0  
                    BEGIN
                            update Person set ForenamesCleansed = @Forenames, SurnameCleansed= @Surname, URNsCleansed=@URNs
                            where reference = @Reference        
                    FETCH NEXT FROM PersonCursor INTO @Forenames, @Surname, @Reference,@URNs
                    END

    CLOSE PersonCursor
    DEALLOCATE PersonCursor
END

我想创建一个触发器，当特定列（称为更新）从0更改为1时触发。这可能吗？

Answer 1

你正在使用Sql Server：

你有两张特别的表：

INSERTED和DELETED。

这些表以这种方式工作：

当您在触发器中应用INSERT语句时，您会找到完整的表INSERTED

当您在触发器中应用UPDATE语句时，您会找到完整的表INSERTED和DELETED

当您在触发器中应用DELETE语句时，您会找到完整的表DELETED

在INSERTED表中，你会发现所有新值，在DELETED中，你会找到旧值，所以当你编写一个触发器时，你可以检查你的布尔字段的旧值和新值，所以当条件满足您可以应用您想要的其他更改。

Answer 2

您只需要在光标逻辑中添加IF：

FETCH NEXT FROM PersonCursor INTO @Forenames, @Surname, @Reference, @URNs
    WHILE @@FETCH_STATUS = 0
        BEGIN
            IF (inserted.[Update] = 0 AND deleted.[Update] = 1) --Added
                BEGIN
                    update Person set ForenamesCleansed = @Forenames, SurnameCleansed= @Surname, URNsCleansed=@URNs
                    where reference = @Reference        
                    FETCH NEXT FROM PersonCursor INTO @Forenames, @Surname, @Reference,@URNs
                END
            END
        END

您可能想要反转逻辑，问题与其标题之间存在不匹配的变化方向。

当单个列（布尔值）从TRUE更新为FALSE时触发的触发器（反之亦然）

2 个答案: