如何获取 table1 用户名以替换为 table2 用户名？

编程问答 2022-05-02

问题描述

表-1

INSERT INTO `r_store`.`tb_user`(`id`,`username`,`password`,`role`,`actions`)
VALUES(1,'ssp','123','ADMIN',1),(2,'RRP',1);

SELECT * FROM r_store.tb_user;

'1','1'
'2','1'

表-2

INSERT INTO `r_store`.`tb_main_product`(`shortname`,`mainproduct`,`tb_user_id`)
VALUES('RR','RAJ',('LK','LAKS',2),('DY','DIYA',5),3);

SELECT * FROM r_store.tb_main_product;

'21','RR','1'
'22','LK','2'
'23','DY','1'
'24','2'
'25','1'
'26','2'
'27','1'
'28','2'

我需要喜欢

'21','ssp'
'22','RRP'
'23','ssp'
'24','RRP'

我尝试过这些查询

SELECT shortname,mainproduct,username FROM tb_main_product left join  tb_user USING (id);
SELECT shortname,username FROM tb_main_product join  tb_user USING (id);

它不起作用，请帮我

解决方法

您必须组合正确的列

SELECT 
    shortname,mainproduct,username
FROM
    tb_main_product tmp
        LEFT JOIN
    tb_user tu ON tu.id = tmp.tb_user_id
foreign-keysjoinjoinmysql