这是一个简易的选课系统。我们可以通过学好、姓名等等来查询出学生的信息。同时也可新增学生信息，最后还可统计出每门课选课的人数-This is a simple elective system. We can learn, name, etc. to check out the student information. Students also can add information, and finally also the statistics of the number of each co