Student
public class Student {
private int id;
private String name;
private int tid;
//老师是一个对象
private Teacher teachers;student里面有teacher对象
teacher
public class Teacher {
private int tid;
private String name;
//学生表是一个集合
List<Student> students;teacher里面有student集合
多对一
<mapper namespace="com.sample.mapper.StudentMapper">
<!-- 按照查询结果-->
<select id="getListStudent" resultMap="getStudentMap">
select * from student
</select>
<resultMap id="getStudentMap" type="student">
<result column="id" property="id"/>
<result column="name" property="name"/>
<!-- property为pojo student里的属性，column映射数据库里的字段-->
<association property="teachers" column="tid" jdbcType="teacher" select="getTeacher"/>
</resultMap>
<select id="getTeacher" resultType="teacher">
select * from teacher where id=#{id}
</select>
<!-- 按照结果集映射-->
<select id="getListStudent" resultMap="getStudentMap1">
select s.id sid,s.name sname,t.id tid,t.name tname
from student s ,teacher t where s.tid=t.id
</select>
<resultMap id="getStudentMap1" type="student">
<result property="id" column="sid"/>
<result property="name" column="sname"/>
<association property="teacher" javaType="Teacher">
<result property="name" column="tname"/>
</association>
</resultMap>
</mapper>一对多
<mapper namespace="com.sample.mapper.TeacherMapper">
<select id="getTeacherInStudent" resultMap="getTeaStu">
select s.id sid,s.name sname,t.id tid,t.name tname
from student s ,teacher t where s.tid=t.id and id=#{tid}
</select>
<resultMap id="getTeaStu" type="teacher">
<result property="id" column="tid"/>
<result property="name" column="tname"/>
<collection property="student" ofType="Student">
<result column="sid" property="id"/>
<result column="sname" property="name"/>
<result column="tid" property="tid"/>
</collection>
</resultMap>
</mapper>