mybatis 一对多查询（集合）

<!--    结果嵌套查询-->
    <resultMap id="TeacherStudent" type="Teacher">
        <result column="tid" property="id"/>
        <result column="tname" property="name"/>
        <collection property="students" ofType="Student" column="id">
            <result column="sid" property="id"/>
            <result column="sname" property="name"/>
            <result column="tid" property="tid"/>
        </collection>
    </resultMap>

    <select id="getTeacher" resultMap="TeacherStudent">
        select s.id sid, s.name sname, t.id tid, t.name tname from student s, teacher t where s.tid = t.id and t.id = #{tid}

    </select>

    <!--=============================================================-->

<!--    按照查询嵌套处理 -->
    <resultMap id="TeacherStudent2" type="Teacher">
        <collection property="students" javaType="ArrayList" ofType="Student" select="getStudent" column="id"/>
    </resultMap>

    <select id="getTeacher2" resultMap="TeacherStudent2">
        select * from teacher where id = #{tid}
    </select>
    <select id="getStudent" resultType="Student">
        select * from student where tid = #{tid}
    </select>