3、建立一个t表，存放班级名称及班级学生人数。然后为Student表创建一个触发器，当Student表中学生信息有变化时，能够自动更新t表的内容。 select class,num= into t
from student group by class create trigger tr1 on student
for as
if update class begin
declare @c nvarchar(20),@n int select @c=class from deleted
select @n=count(*) from student
where class= update t set num=@n where class=@c select @c=class
from select @n=count(*) from student where class=@c
set num=@n where class=@c end