自己写的数据库，包含增删改查基本功能，可设置主键，唯一性等，使用方法在实验报告里有，每个数据库对应一个无后缀的文件-database designed by myself ,with add,delete,alter,check etc basic functions ,primary key and unique can be set,every database refers to one data file,using method is enclosed in the paper