mybatis兩種嵌套查詢方式

1，推薦用第一種

<select id="getTeacher2" resultMap="TeacherStudent">
    select s.id sid,s.name sname,t.id tid,t.name tname
    from teacher t,student s
    where s.tid=tid and tid=#{tid}
</select>

<resultMap id="TeacherStudent" type="Teacher">
    <result property="id" column="tid"/>
    <result property="name" column="tname"/>
    <collection property="students" ofType="Student">
        <result property="id" column="sid"/>
        <result property="name" column="sname"/>
        <result property="tid" column="tid"/>
    </collection>
</resultMap>

2,

<select id="getTeacher2" resultMap="TeacherStudent">
    select * from mybatis.teacher where id = #{id}
</select>

<resultMap id="TeacherStudent" type="Teacher">
    <collection property="students" javaType="ArrayList" ofType="Student" select="getStudentByTeacherId" column="id"/>
</resultMap>

<select id="getStudentByTeacherId" resultType="Student">
    select * from mybatis.student where tid = #{tid}
</select>