mybatis实现级联查询一对一

系统管理员 2024-03-24 14:58 89阅读 0赞

接口形式

package com.hspedu.mapper;
    
    import com.hspedu.entity.Person;
    
    public interface PersonMapper {
        //通过person的id获取到Person，包括这个Person关联的IdenCard对象【级联查询】
        public Person getPersonById(Integer id);
    
    
        //通过person的id获取到Person，包括这个Person关联的IdenCard对象【级联查询】 方式2
        public Person getPersonById2(Integer id);
    
    
        //需要在PersonMapper新建一个方法来解决idenCard反向查询得到Person对象/数据
        public Person getPersonByCardId(Integer cardId);
    }

xml文件形式

<?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.hspedu.mapper.PersonMapper">
    
        
        <resultMap id="PersonResult" type="Person">
    
    
            <id property="id" column="id"/>
            <result property="name" column="name"/>
    
            <association property="card" javaType="IdenCard">
                <result property="id" column="id"/>
                <result property="card_sn" column="card_sn"/>
    
            </association>
    
        </resultMap>
    
        <select id="getPersonById" parameterType="Integer" resultMap="PersonResult">
    SELECT * FROM `person`,`idencard` WHERE person.id = #{id} AND person.card_id =  idencard.id
        </select>
    
    
        <resultMap id="PersonResultMap2" type="Person">
            <id property="id" column="id"/>
            <result property="name" column="name"/>
    
    
            <association property="card" column="card_id"
    
                         select="com.hspedu.mapper.IdenCardMapper.getIdenCardById"/>
    
        </resultMap>
        <select id="getPersonById2" parameterType="Integer" resultMap="PersonResultMap2">
            SELECT * FROM `person` WHERE `id` = #{id}
        </select>
    
    
    
    
    
    
        <select id="getPersonByCardId" parameterType="Integer" resultType="Person">
                SELECT * FROM person WHERE `card_id` = #{id}
    
        </select>
    
    
    
    </mapper>

下面是idenCard的接口形式

public interface IdenCardMapper {
       //根据id获取到身份证序列号
        public IdenCard getIdenCardById(Integer id);
    
    
    
        //根据id级联查询到Person【作业】
    
        public IdenCard getIdenCardById2(Integer id);
    
    
    
    
    }

下面是xml