触发器

Create table LogInfo
(
Id uniqueidentifier unique,
content text null,
Inputdate datetime not null,
)
alter table LogInfo add constraint constraint_Id default newid() for Id
alter table LogInfo add constraint constraint_Inputdate default getdate() for Inputdate

if(exists(select 1 from sys.objects where name='update_forbidden'))
    drop trigger update_forbidden
GO    
create trigger update_forbidden
    on studentinfo_2019
    after update
as
begin
    if(update(name))
    begin
        begin try
            declare @oldname varchar(50),@newname varchar(50),@studentId varchar(50)
            set @oldname = (select Name from deleted)
            set @newname = (select Name from inserted)
            set @studentId = (select studentId from deleted)
            insert into LogInfo (content) values('学号为 '+@studentId+' 的姓名 由 ' + @oldname +' 改为 '+@newname)
        end try
        begin catch
            rollback transaction
        end catch
    end
end

if(exists(select 1 from sys.objects where name='delete_forbidden'))
    drop trigger delete_forbidden
GO    
create trigger delete_forbidden
    on studentinfo_2019
    after delete
as
begin
    RAISERROR('禁止直接删除该表数据，操作被禁止',1,1)--raiserror 是用于抛出一个错误
    rollback transaction
end

inserted 和 deleted 虚拟表 作为表存在 而不是变量