数据库的数据项主要数据包括：学号、姓名、年级、专业、成绩1、成绩2、成绩3、平均成绩、总成绩。

要求具有以下功能：

（1）添加、删除任意个记录。

（2）修改任意个记录。

（3）显示、保存记录。　　

（4）排序功能：打开学生数据库，计算每个学生的平均成绩和总成绩，用冒泡法或选择排序法将平均成绩和总成绩排序后生成两个新文件（从大到小），存盘并显示这两个文件的全部记录。

（5）查询功能：打开总成绩排序文件，用折半查找法统计出给定分数的人数并显示。

-Database of data items mainly include: student id, name of data, grade, professional, 1, 2, 3, the average scores and grade.

Request has the following features:

(1) add, delete arbitrary a record.

(2) modify any records.

(3) show, keep records.

(4) sorting function: open database, each student achievement and the average student with bubbles or overall, choose ranking will average scores and grade two new file after sorting from large to small (that), save the two files and records of all.