六步学会mybatis---------第四章：resultMap处理 多表联合之联表查询_extends=、baseresultmap

<resultMap>标签下的子标签
<association>处理单个对象数据
<collection>处理多个对象
1
2
3

1. 一对一

Student类

public class Student {
   
    private Integer id;
    private String name;
    private Integer age;
    // 一对一
    private Computer computer;
    //...省略
    }
1
2
3
4
5
6
7
8
9

Computer类

public class Computer {
   
    private Integer id;
    private String moudle;
    }
1
2
3
4
5

数据库里学生和电脑信息在两张表里存储


要求查出学生时，把电脑信息也查出来

<select id="selAll" resultMap="StudentResultMap">
        select s.`s_id`,s.`s_name`,s.`s_age`,s.`c_id`,c.`c_moudle`
            from student s inner join computer c where s.`c_id`=c.`c_id`
    </select>

    <!--一对一-->
    <resultMap id="StudentResultMap" type="Student">
        <id column="s_id" property="id"></id>
        <result column="s_name" property="name"></result>
        <result column="s_age" property="age"></result>
        <association property="computer" javaType="Computer">
            <id column="c_id" property="id"></id>
            <result column="c_moudle" property=
1
2
3
4
5
6
7
8
9
10
11
12