/*(35)建立一个存储过程，输入一个学生的姓名，返回该学生全部必修课课程的平均成绩。*/drop procedure if exists ppp;delimiter $$create procedure ppp( $name varchar(20), out $avg decimal(10,2))begin with tmp as( select avg(score) avg from grades a join courses b using(courseid) where a.studentid=(select studentid from students where name=$name) and b.majors='' or b.majors like '%a%') select cast(avg as decimal(10,2)) into $avg from tmp;end $$delimiter ;call ppp('陈蓉',@avg);select @avg;有哪位大神知道这个提示是什么意思吗？这道题该咋写啊