1. 输出所有数据，也可以根据学号，姓名，输出某些数据2.可以增加，删除，修改记录3：能按照，学号，姓名，和成绩进行排序 -1. Output all the data, but also can learn its name, the output of certain data 2. Can add, delete, modify records 3: in accordance with the school number, name, and sort result