注解实现一对多映射

@Results({
        @Result(id = true, column = "tid", property = "tid"),
        @Result(column = "name", property = "name"),
        @Result(column = "tid", property = "studentList", many =
            @Many(select = "getStudentByTid")
        )
})
@Select("select * from teacher where tid = #{tid}")
Teacher getTeacherBySid(int tid);
 
@Select("select * from student inner join teach on student.sid = teach.sid where tid = #{tid}")
List<Student> getStudentByTid(int tid);

其中 @Many 是一个子查询，这里就根据老师教授学生的id来查询对应的学生信息，等同于：

<resultMap id="asTeacher" type="Teacher">
    <id column="tid" property="tid"/>
    <result column="tname" property="name"/>
    <collection property="studentList" ofType="Student">
        <id property="sid" column="sid"/>
        <result column="name" property="name"/>
        <result column="sex" property="sex"/>
    </collection>
</resultMap>