在线考试的数据库设计图，从老师到学生的所有关系和老师与学生的权限-Online examination database design, from teachers to students and teachers with all the rights of students

系统权限、角色管理，详细的设计各种实体间的关系，数据库表字段都设计出来了。-System access, the role of management, detailed design of the relationship between two entities, database table fields design out.