Mybatis-puls配置 多表查询

mybatis-puls

mybatis-plus依赖

        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.1
        

application.yml配置

server:
  port: 8003
spring:
  datasource:
    url: jdbc:mysql:/IP地址//数据库?serverTimezone=GMT%2B8&CharacterEncoding=utf8
    username: 账号
    password: 密码
mybatis-plus:
# 扫描xml文件
  mapper-locations: classpath:/mapper/*.xml
  configuration:
# 控制台打印执行SQL语句
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

启动类扫描mapper

@SpringBootApplication
//扫描
@MapperScan("com.jsd.mapper")
public class Springcloud03Application {

    public static void main(String[] args) {
        SpringApplication.run(Springcloud03Application.class, args);
    }

}

pojo

User

@Data
//数据库表名
@TableName("user")
public class User implements Serializable {
    private Integer Id;
    private String Name;
    private Integer Age;
    private String Email;
//对象
    private Message message;
//嵌套集合
    private List messageList;

}

Message

@Data
@TableName("message")
public class Message implements Serializable {
    private Integer Id;
    private String Message;
}

UserMapper接口

//继承BaseMapper<>
public interface UserMapper extends BaseMapper{

    List selectAll();

    List selectLists();
}

UserMapper.xml文件

    
        
        
        
        
        
            
            
        
    
    
        
        
        
        
        
            
            
        
    
    
        select
        a.id,a.name,a.age,a.email,b.message
        from user a join message b
        on a.id=b.id
    
    
        select
        a.id,a.name,a.age,a.email,b.message
        from user a join message b
        on a.id=b.id