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  • MyBatis中的 One to One

    1需求:根据id查询学生的身份证信息

    学生实体Bean

    public class Student {
        private Integer id;
        private String name;
        private Card card;  //关联的身份证对象

    学生的Mapper(注意当学生类中包含其他类的bean对象时映射的写法!! 学生类中包含了 Card对象)

    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
    <mapper namespace="com.cn.entity2.Student" >
        <resultMap id="studentMapper" type="com.cn.entity2.Student">
            <id property="id" column="id"></id>
            <result property="name" column="name"></result>      
    
            <association property="card" resultMap="com.cn.entity2.Card.cardMapper"></association>
        </resultMap>
    
    
        <select id="findByid" parameterType="int" resultMap="studentMapper">
            select s.id,s.name,c.cid,c.cunm
            from
            student s inner join cards c
            on s.scid = c.cid and s.id = #{id}
        </select>
    
    </mapper>

    身份证Bean

    public class Card {
        private Integer cid;
        private String cunm;

    身份证Mapper

    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
    
    <mapper namespace="com.cn.entity2.Card" >
        <resultMap id="cardMapper" type="com.cn.entity2.Card">
            <id property="cid" column="cid"></id>
            <result property="cunm" column="cunm"></result>
        </resultMap>
    </mapper>
    坚持
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  • 原文地址:https://www.cnblogs.com/gaoSJ/p/13049607.html
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