能实现简单的成绩查询！！重要的是练习大家对项目的认识-To achieve a simple query results! ! Is important that we practice awareness of the project! !

用于学生成绩查询，修改等，用户有学生，教师，管理员-FOR SEARCHING,UPDATING, AND SO ON

提醒用户输入课程名称，学生姓名，学生成绩，并对学生成绩计算总分，平均分，并排名。-To remind the user to enter the course name, student name, student achievement, and the calculation of student achievement scores, the average score and ranking.