Mybatis中ResultMap解决属性名和数据库字段名不一致问题

目录

• 前言
• 1. 字段名不一致
• 解决方法:
  
• 第一种方式: 起别名
  
• 第二种方式: 结果集映射 resultMap
  
• 2. 多对一处理
• 3. 一对多处理
• 小结

public class User {

    private int id;
    private String name;
    private String password;

    select id,name,pwd as password from user1 where id = #{id};

    
    
    
    




    select * from user1 where id = #{id};

    
  
    




    select * from user1 where id = #{id};

CREATE TABLE `teacher`(

   `id` INT(10) NOT NULL,
   `name` VARCHAR(30) DEFAULT NULL,
   PRIMARY KEY (`id`)
)ENGINE = INNODB DEFAULT CHARSET=utf8

INSERT INTO teacher(`id`,`name`) VALUES(1,"zs");


CREATE TABLE `student`(

   `id` INT(10) NOT NULL,
   `name` VARCHAR(30) DEFAULT NULL,
   `tid` INT(10) DEFAULT NULL,
    PRIMARY KEY(`id`),
    KEY `fktid` (`tid`),
    CONSTRAINT `fktid` FOREIGN KEY (`tid`) REFERENCES `teacher`(`id`)
)ENGINE=INNODB DEFAULT CHARSET=utf8


INSERT INTO `student`(`id`,`name`,`tid`) VALUES("1","小明","1");
INSERT INTO `student`(`id`,`name`,`tid`) VALUES("2","小红","1");
INSERT INTO `student`(`id`,`name`,`tid`) VALUES("3","小张","1");
INSERT INTO `student`(`id`,`name`,`tid`) VALUES("4","小李","1");
INSERT INTO `student`(`id`,`name`,`tid`) VALUES("5","小工","1");

 
    
        
        
            mysql
            mysql-connector-java
            5.1.46
        
        
        
            org.mybatis
            mybatis
            3.5.2
        
        
        
            junit
            junit
            4.13
        
        
        
            org.projectlombok
            lombok
            1.18.8
        
    

    
    
        
            
                src/main/resources
                
                    **/*.properties
                    **/*.xml
                
                true
            
            
                src/main/java
                
                    **/*.properties
                    **/*.xml
                
                true
            
        
    

driver = com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/mybatis&＃63;useSSL=true&useUnicode=true&characterEncoding=UTF-8
username = root

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


    
    
    
   

    
    
       
    

    
        
            
            
                
                
                
            
        

    

    
        
        
        
    

package com.gs.pojo;

import lombok.Data;

/**
 * @Auther: Gs
 * @Date: 2020/6/9
 * @Description: com.com.com.gs.pojo
 * @version: 1.0
 */
@Data
public class Student {

    private int id;
    private String name;
    //组合进来一个老师
    private Teacher teacher;

}

package com.gs.pojo;

import lombok.Data;

/**
 * @Auther: Gs
 * @Date: 2020/6/9
 * @Description: com.com.com.gs.pojo
 * @version: 1.0
 */
@Data
public class Teacher {

    private int id;
    private String name;

}

public interface StudentMapper {

    //查询所有的学生信息,以及对应的的老师的信息
    public List getStudent();
}    

    select s.id sid, s.name sname, t.name tname
    from student s, teacher t
    where s.tid = t.id



    
    
    
        
    

select s.id sid, s.name sname, t.name tname
   from student s, teacher t
   where s.tid = t.id

    select * from student;


    
    
    
    



    select * from teacher where id = #{id};

    select * from student;

    select * from teacher where id = #{id};

@Data
public class Student {
	//学生id
    private int id;
    //学生姓名
    private String name;
    //教师id
    private int tid;
}

@Data
public class Teacher {

    private int id;
    private String name;

    //一个老师有多个学生
    private List students;

}

//获取指定老师下所有学生及老师的信息
Teacher getTeacher(@Param("tid") int id);

    select s.id sid, s.name sname, t.id tid, t.name tname from student s, teacher t
    where s.tid = t.id and  t.id = #{tid}

    select s.id sid, s.name sname, t.id tid, t.name tname from student s, teacher t
    where s.tid = t.id and  t.id = #{tid}


    
    
    
    
        
        
        
    

    select * from teacher where id = #{tid}

    select * from student where tid=#{id}

    select * from teacher where id = #{tid}


    
    


    select * from student where tid=#{id}