Java PO類中有List，Map或者其他的類做成員，mybatis做dao層譬如 Class Student{     int id;      School school;     List<String> courses;     List<Teacher> teachers;     Map<String, List<Integer>> courseScores;  }    其中School， Teacher是其他PO類在mysql設(shè)計(jì)一個(gè)表t_student，那么school, teachers，courses,courseScores對應(yīng)字段, 如何設(shè)計(jì)？school和teacher就直接用school_id, teacher_id外鍵嗎？那courses, courseScores呢？