select student.stu_name,max(score.number) from student
                inner join score on student.stu_id = score.student_id
                inner join course on score.course_id = course.cou_id
                inner join teacher on course.teacher_id = teacher.tea_id
                where teacher.tea_name ="杨艳";

ERROR 1055 (42000): Expression #1 of SELECT list is not in GROUP BY clause and
contains nonaggregated column ‘oldboy.student.stu_name‘ which is not functionally dependent
on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by