今要建立关于系、学生、班级、学会等诸信息的一个关系数据库。一个系有若干专业，每个专业每年只招一个班，每个班有若干学生。一个系的学生住在同一宿舍区。每个学生可参加若干学会，每个学会有若干学生。学生参加某学会有一个入会年份。-Today to build on, student, class, to learn the information such as a relational database. A department has several specialty, each only a class, every year there are a number of students in each class. A department of the pupils live in the same dorm. Every student can participate in a number of society, every society has several students. Students attend a society have a year of membership.