【简答题】 请为以下代码加上注释。 create trigger tr_delete on student for delete begin declare @bh char(5) select @bh=deleted.sno from deleted delete from studentcourse where sno=@bh end

-- 创建名为tr_delete的触发器，当对student表进行删除操作时触发
create trigger tr_delete
on student
for delete
begin
    -- 声明一个变量@bh，类型为char(5)
    declare @bh char(5)

    -- 从被删除的记录中获取sno字段的值，并赋值给@bh变量
    select @bh=deleted.sno from deleted

    -- 在studentcourse表中删除sno等于@bh变量的记录
    delete from studentcourse where sno=@bh
end