多对一的处理：
<!--方法一 根据结构查询 联表 -->
<select id="getStudent2" resultMap="StudentTeacher2">
select s.id sid,s.name sname,t.name tname from student s,teacher t where s.tid=t.id;
</select>
<resultMap id="StudentTeacher2" type="Student">
<result property="id" column="sid"/>
<result property="name" column="sname"/>
<association property="teacher" javaType="Teacher">
<result property="name" column="tname"/>
</association>
</resultMap>
<!-- 方法二 子查询 嵌套-->
<select id="getStudent" resultMap="StudentTeacher">
select * from student ;
</select>
<resultMap id="StudentTeacher" type="Student">
<result property="id" column="id"/>
<result property="name" column="name"/>
<!-- 复杂的属性，我们需要单独处理 对象：association 集合：collection-->
<association property="teacher" column="tid" javaType="Teacher" select="getTeacher"/>
</resultMap>
<select id="getTeacher" resultType="Teacher">
select * from teacher;
</select>
一对多的处理：
标签：name,id,查询,student,Mybatis,一对,teacher,select From： https://www.cnblogs.com/kidzxy/p/16817256.html