数据库实验报告

说明：  实现学生与课程之间的选修关系： 一名学生可以选修多门课程；一门课程可以被多名学生选修； 描述学生的属性有：学号，姓名，性别，专业，班级，年级等 描述课程的属性有：课程号，课程名，先修课程号，课程学分，开课单位等 描述选修除了需要指明哪个学生选修了哪门课程，还需要描述该生选修该课程的最终成绩。
(The elective relationship between students and courses: One student can take more than one course, and one course can be chosen by more than one student. The attributes describing students are: student number, name, gender, major, class, grade, etc. The attributes of describing the course are: course number, course name, pre-course number, course credits, course opening unit, etc. Describing the elective course requires not only specifying which student has taken which course, but also describing the final result of the student's elective course.)