数据库系统上机实验一到实验四报告，数据表的创建到维护、权限操作都用SQL语言代码完成，报告完整，结构清晰，内含数据库上机实验指导书。(The database system is on the machine experiment one to the experiment four report, the data table creation, the maintenance, the permission operation is completed by the SQL language code, the report is complete, the structure is clear, contains the database machine experiment instruction book.)