database - 如何在没有公共列的情况下使用链接表连接表

Question

我们如何加入这些 student_info 和 class_info 表，没有公共列，但两个外键都存储在 class_student 表中。

Answer 1

调整以适合您的 WHERE 子句、特定数据库和 JOIN 需求。

对于学生的课程：

SELECT *
FROM student_info JOIN class_student ON student_info.student_id = class_student.student_id
                  JOIN class_info    ON class_student.class_id  = class_info.class_id
WHERE student_info.student_id = ...

对于班级的学生：

 SELECT *
 FROM class_info JOIN class_student ON class_info.class_id      = class_student.class_id
                 JOIN student_info  ON class_student.student_id = student_info.student_id
 WHERE class_info.class_id = ...