• springboot+mybatis实现一对一，一对多

    文章目录

    一对一

    准备工作

    数据库表

    DROP TABLE IF EXISTS `account`;
CREATE TABLE `account` (
  `id` varchar(100) DEFAULT NULL,
  `uid` varchar(100) DEFAULT NULL,
  `money` decimal(10,0) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

INSERT INTO `account` VALUES ('1','41',10000),('2','42',20000),('3','43',30000);

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` varchar(100) DEFAULT NULL,
  `user_name` varchar(100) DEFAULT NULL,
  `birthday` date DEFAULT NULL COMMENT '生日',
  `sex` varchar(100) DEFAULT NULL,
  `address` varchar(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

INSERT INTO `user` VALUES ('41','小王','2022-02-27','男','河南'),('42','小李','2021-07-01','女','江苏'),('43','小红','2019-08-01','女','湖北');

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    实体类

    Account.java

    package com.jack.springbootmybatis.pojo;

import org.springframework.format.annotation.DateTimeFormat;

import java.util.Date;

public class Account {
    /**
     * @description 编号
     */
    private String id;
    /**
     * @description 用户名
     */
    private String userName;
    /**
     * @description 生日
     */
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private Date birthday;
    /**
     * @description 性别
     */
    private String sex;
    /**
     * @description 家庭住址
     */
    private String address;

    private User user;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id='" + id + '\'' +
                ", userName='" + userName + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                ", user=" + user +
                '}';
    }
}


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    User.java

    package com.geekmice.onetomany.bo;

import java.util.Date;

public class User {
    /**
     * @description 用户编号
     */
    private String id;
    /**
     * @description 用户名
     */
    private String userName;
    /**
     * @description 出生年月日
     */
    private Date birthday;
    /**
     * @description 性别
     */
    private String sex;
    /**
     * @description 家庭地址
     */
    private String address;

    private Account account;

    public Account getAccount() {
        return account;
    }

    public void setAccount(Account account) {
        this.account = account;
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", userName='" + userName + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                ", account=" + account +
                '}';
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

}


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    对应的xml

    AccountToUserMapper.xml

    
DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.geekmice.onetomany.dao.IUserAccountDao" >
    <resultMap id="userAccountMap" type="com.geekmice.onetomany.bo.User">
        <id property="id" column="id"/>
        <result property="userName" column="user_name"/>
        <result property="birthday" column="birthday"/>
        <result property="sex" column="sex"/>
        <result property="address" column="address"/>
        <association property="account" javaType="com.geekmice.onetomany.bo.Account">
            <result property="uId" column="uid"/>
            <result property="money" column="money"/>
        association>
    resultMap>
    <select id="getAccountByUser" resultMap="userAccountMap">
     SELECT
        a.uid,
        a.money,
        b.user_name,
        b.id,
        b.birthday,
        b.sex,
        b.address
    FROM
        account a
    LEFT JOIN `user` b
            ON
        a.uid = b.id
        <where>
            <if test="userName != null and userName != '' ">
              and  b.user_name = #{userName}
            if>
        where>

    select>
mapper>

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    对应的controller

    
@RestController
public class UserAccountController {
    @Resource
    private IUserAccountDao iUserAccountDao;

    @PostMapping("/getAccountByUser")
    public User getAccountByUser(@RequestBody User user){
        return iUserAccountDao.getAccountByUser(user);
    }
}


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    postman调用
    在这里插入图片描述

    一对多

    理解：
    一个学生对应多门科目成绩

    数据库表

    DROP TABLE IF EXISTS `tmp_student`;

CREATE TABLE `tmp_student` (
  `id` varchar(100) DEFAULT NULL,
  `name` varchar(100) DEFAULT NULL,
  `t_id` varchar(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

INSERT INTO `tmp_student` VALUES ('1','小王','1'),('2','小红','2'),('3','小张','2'),('4','小李','2'),('5','小黄','5'),('1','小王','1'),('2','小红','2'),('3','小张','2'),('4','小李','2'),('5','小黄','5');


DROP TABLE IF EXISTS `tmp_teacher`;

CREATE TABLE `tmp_teacher` (
  `id` varchar(100) DEFAULT NULL,
  `name` varchar(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

/*!40000 ALTER TABLE `tmp_teacher` DISABLE KEYS */;
INSERT INTO `tmp_teacher` VALUES ('1','王老师'),('2','刘老师'),('3','张老师'),('4','陆老师'),('5','华老师');




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    实体类

    TmpTeacher.java

    package com.geekmice.onetomany.bo;

import java.util.List;

public class TmpTeacher {
    /**
     * @descripton 教师编号
     */
    private String tId;
    /**
     * @description 教师名
     */
    private String name;
    private List<TmpStudent> studentList;

    public String gettId() {
        return tId;
    }

    public void settId(String tId) {
        this.tId = tId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<TmpStudent> getStudentList() {
        return studentList;
    }

    public void setStudentList(List<TmpStudent> studentList) {
        this.studentList = studentList;
    }

    @Override
    public String toString() {
        return "TmpTeacher{" +
                "tId='" + tId + '\'' +
                ", name='" + name + '\'' +
                ", studentList=" + studentList +
                '}';
    }
}


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    TmpStudent .java

    package com.geekmice.onetomany.bo;

import java.util.List;

public class TmpStudent {
    /**
     * @description 学生编号
     */
    private String id;
    /**
     * @description 学生姓名
     */
    private String name;


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "TmpStudent{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                '}';
    }
}


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    对应dao层

    package com.geekmice.onetomany.dao;

import com.geekmice.onetomany.bo.TmpTeacher;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface ITeacherStudentDao {
    TmpTeacher getTeacherInfo();
}



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    对应xml

    
DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.geekmice.onetomany.dao.ITeacherStudentDao">
    <resultMap id="teacherStudentInfo" type="com.geekmice.onetomany.bo.TmpTeacher">
        <id column="bId" property="tId"/>
        <result column="teaName" property="name"/>
        <collection property="studentList" ofType="com.geekmice.onetomany.bo.TmpStudent">
            <result column="stuName" property="name"/>
            <result column="aId" property="id"/>
        collection>
    resultMap>
    <select id="getTeacherInfo" resultMap="teacherStudentInfo" >
        SELECT
            b.id bId,
            a.id aId,
            a.name stuName,
            b.name teaName
        FROM
            tmp_student a
        LEFT JOIN tmp_teacher b
        ON
            a.t_id = b.id
            where   b.name = '刘老师'





    select>
mapper>

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    对应controller

    package com.geekmice.onetomany.controller;

import com.geekmice.onetomany.bo.TmpTeacher;
import com.geekmice.onetomany.dao.ITeacherStudentDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TeacherStudentController {
    @Autowired
    private ITeacherStudentDao iTeacherStudentDao;

    @GetMapping("/getTeacherInfo")
    public TmpTeacher getTeacherInfo() {
        return iTeacherStudentDao.getTeacherInfo();
    }
}


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    postman调用

    在这里插入图片描述

    参考博客

    1.mybatis一对多&&多对一处理

    2.MyBatis 实现一对多有几种方式,怎么操作的？

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  • 原文地址：https://blog.csdn.net/greek7777/article/details/126219551