SQL 触发器 关于学生选课

Question

创建一个触发器，当学生进行选课表“stucou”操作（选课，取消选课，改选课）时，能够自动改变相应课程的选课人数(course表下的chonum) STUCOU表中有 学号STUNO,课程号COUNO COURSE表中有 课名COUNAME,COUNO,选课人数CHONUM 谢谢了~初学者~

Answer 1

create trigger <triggername> on stucou for insert as begin declare @n int select @n = couno from inserted update course set chonum = chonum + 1 where couno = @n end create trigger <triggername> on stucou for delete as begin declare @n int select @n = couno from deleted update course set chonum = chonum - 1 where couno = @n end create trigger <triggername> on stucou for update as begin declare @n int declare @m int if update(couno) begin select @n = couno from inserted select @m = couno from deleted update course set chonum = chonum + 1 where couno = @n update course set chonum = chonum - 1 where couno = @m end end