系列九、MyBatis一对一级联更新问题

一、概述

        日常工作中经常会涉及到一对一级联更新的问题，例如：更新员工信息时也需要更新员工所在的部门信息，那么这种情况下就涉及到了MyBatis的级联更新问题。

二、代码实战

2.1、pom 

<dependencies>
	<!-- springboot -->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-devtools</artifactId>
	</dependency>

	<!-- 数据源 -->
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>8.0.26</version>
	</dependency>
	<dependency>
		<groupId>org.mybatis.spring.boot</groupId>
		<artifactId>mybatis-spring-boot-starter</artifactId>
		<version>2.3.1</version>
	</dependency>
	<dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>druid-spring-boot-starter</artifactId>
		<version>1.1.10</version>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-data-redis</artifactId>
	</dependency>

	<!-- 工具 -->
	<dependency>
		<groupId>org.projectlombok</groupId>
		<artifactId>lombok</artifactId>
		<version>1.18.30</version>
	</dependency>
	<dependency>
		<groupId>cn.hutool</groupId>
		<artifactId>hutool-all</artifactId>
		<version>5.8.21</version>
	</dependency>
	<dependency>
		<groupId>org.apache.commons</groupId>
		<artifactId>commons-lang3</artifactId>
	</dependency>
	<dependency>
		<groupId>org.apache.commons</groupId>
		<artifactId>commons-collections4</artifactId>
		<version>4.4</version>
	</dependency>
	<dependency>
		<groupId>com.alibaba.fastjson2</groupId>
		<artifactId>fastjson2</artifactId>
		<version>2.0.25</version>
	</dependency>

</dependencies>

2.2、yml

server:
  port: 9999

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/20231018_redis?useSSL=false&useUnicode=true&characterEncoding=UTF8&serverTimezone=GMT
    username: root
    password: 123456

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: org.stat.entity.model
  configuration:
    map-underscore-to-camel-case: true

logging:
  level:
    org:
      star:
        mapper: debug

2.3、主启动

/**
 * @Author : 一叶浮萍归大海
 * @Date: 2023/12/10 12:44
 * @Description:
 *
 */
@MapperScan(basePackages = "org.star.mapper")
@SpringBootApplication
public class SpringbootMybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootMybatisApplication.class, args);
    }


}

2.4、DepartmentDO

/**
 * @Author : 一叶浮萍归大海
 * @Date: 2023/12/10 12:48
 * @Description:
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
@Accessors(chain = true)
@ToString(callSuper = true)
public class DepartmentDO implements Serializable {
    /**
     * 编号
     */
    private Integer id;

    /**
     * 部门名称
     */
    private String departmentName;

}

2.5、EmployeeDO

/**
 * @Author : 一叶浮萍归大海
 * @Date: 2023/12/10 15:38
 * @Description:
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
@Accessors(chain = true)
@ToString(callSuper = true)
public class EmployeeDO implements Serializable {
    /**
     * 员工编号
     */
    private Integer id;

    /**
     * 姓名
     */
    private String name;

    /**
     * 年龄
     */
    private Integer age;

    /**
     * 部门
     */
    private DepartmentDO department;

}

2.6、EmployeeMapper

/**
 * @Author : 一叶浮萍归大海
 * @Date: 2023/12/10 15:40
 * @Description:
 */
public interface EmployeeMapper {

    /**
     * 级联更新员工信息（更新员工信息 & 部门信息）
     * @param param
     */
    void updateEmployeeCascade(EmployeeDO param);

}

2.7、EmployeeMapper.xml

<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="org.star.mapper.EmployeeMapper">

    <update id="updateEmployeeCascade">
        update employee e left join department d
        on e.department_id = d.id
        <set>
            <if test="name != null and name != ''">
                e.name = #{name},
            </if>
            <if test="age != null">
                e.age = #{age},
            </if>
            <if test="department.departmentName != null and department.departmentName != ''">
                d.department_name = #{department.departmentName}
            </if>
        </set>
        where e.id = #{id}
    </update>

</mapper>

2.8、EmployeeMapperTest

/**
 * @Author : 一叶浮萍归大海
 * @Date: 2023/12/10 15:42
 * @Description:
 */
@SpringBootTest
public class EmployeeMapperTest {

    @Autowired
    private EmployeeMapper employeeMapper;

    @Test
    public void updateEmployeeTest() {
        EmployeeDO employeeDO = new EmployeeDO()
                .setId(2)
                .setName("刘亦菲")
                .setAge(18)
                .setDepartment(
                        new DepartmentDO()
                                .setId(2)
                                .setDepartmentName("市场部222")
                        );
        employeeMapper.updateEmployeeCascade(employeeDO);
    }

}