SQL Server触发器以及如何在SQL Server Manager中调试触发器

·只有inserted表有数据时，当前操作为insert；
·inserted和deleted两张表都有数据时，当前操作为update；
·只有deleted表有数据时，当前操作为delete。

1.

CREATE TRIGGER trTask_Update ON dbo.Task
    FOR UPDATE
AS
    BEGIN

        DECLARE @TaskId INT
        DECLARE @NewTaskOrder INT
        DECLARE @WorkstreamId INT
        DECLARE @OldTaskOrder INT

--update
        BEGIN
            SELECT  @TaskId = id ,
                    @OldTaskOrder = TaskOrder ,
                    @WorkstreamId = WorkstreamId
            FROM    deleted

            SELECT  @NewTaskOrder = TaskOrder
            FROM    dbo.Task
            WHERE   Id = @TaskId
--When updating a row, if old value is greater than new value, then +1 all values that are >= the new value and < the old value
            IF @OldTaskOrder > @NewTaskOrder
                BEGIN
                    UPDATE  dbo.Task
                    SET     TaskOrder = TaskOrder + 1
                    WHERE   WorkstreamId = @WorkstreamId
                            AND TaskOrder >= @NewTaskOrder
                            AND TaskOrder < @OldTaskOrder
                            AND Id <> @TaskId
                END

            IF @OldTaskOrder < @NewTaskOrder
                BEGIN                     

                    UPDATE  dbo.Task
                    SET     TaskOrder = TaskOrder - 1
                    WHERE   WorkstreamId = @WorkstreamId
                            AND TaskOrder <= @NewTaskOrder
                            AND TaskOrder > @OldTaskOrder
                            AND Id <> @TaskId
                END

        END

    END

　　

2.

CREATE TRIGGER trTask_Insert ON dbo.Task
    FOR INSERT
AS
    BEGIN

        DECLARE @TaskId INT
        DECLARE @NewTaskOrder INT
        DECLARE @WorkstreamId INT
        DECLARE @OldTaskOrder INT

--insert
        BEGIN
            SELECT  @TaskId = id ,
                    @NewTaskOrder = TaskOrder ,
                    @WorkstreamId = WorkstreamId
            FROM    INSERTED
--When inserting a new,+1 to all task orders that are equal to or greater than the newly inserted task's task order
            UPDATE  dbo.Task
            SET     TaskOrder = TaskOrder + 1
            WHERE   WorkstreamId = @WorkstreamId
                    AND TaskOrder >= @NewTaskOrder
                    AND Id <> @TaskId

        END

    END

　　

3.如何调试触发器：

一、打开SQL查询分析器
二、将以下Sql语句复制到查询窗口并运行
use pubs

CREATE  trigger trigger_update on authors
for update
as
begin
 print('update lastname=hoho')
end

CREATE    proc Authors_procInsert
as 
begin
 update  authors set au_lname='HOHO' where au_id='172-32-1176'
end

三、在左边的对象浏览器中选择pubs->存储过程在Authors_procInsert(如未出现请刷新pubs数据库）上右击‘Execute stored procedure’，设置参数点击确定打开生成的执行存储过程的脚本 -> 点击SQL Server Management 菜单上的Debug -> Start Debugging...
四、当运行到" update  authors set au_lname='HOHO' where au_id='172-32-1176'“时按“F11”即进入触发器代码