Mysql 如何将table1用户名替换为table2用户名？

表-1

选择*FROM r_store.tb_user

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

表-2

'1','SSP','123','ADMIN','1'
'2','RRP','123','ADMIN','1'

从r_store.tb_main_产品中选择*

INSERT INTO `r_store`.`tb_main_product`(`shortname`,`mainproduct`,`tb_user_id`)
VALUES('RR','RAJ',1),('LK','LAKS',2),('DY','DIYA',5),('DY','DIYA',3);

我需要像

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

我试过这些问题

'21','RR','RAJ','SSP'
'22','LK','LAKS','RRP'
'23','DY','DIYA','SSP'
'24','DY','DIYA','RRP'

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它不起作用请帮助我你必须合并正确的列

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

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‘RR’、‘RAJ’、‘SSP’、‘LK’、‘LAKS’、‘RRP’、‘DY’、‘DIYA’、‘NULL’DY’、‘DIYA’、‘NULL’RR’、‘RAJ’、‘SSP’、‘LK’、‘LAKS’、‘RRP’、‘DY’、‘DIYA’、‘NULLyes’这是左连接所做的，它结合了两个选项卡，即使tb_main__产品没有相应的patner，请在评论时详细解释您的问题

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