参考链接

1. nohup.net博主：https://nohup.net/?id=133

更新（保留）为原值（反引号），即如果原值是0，那么执行后是0

INSERT INTO user_admin_t (_id, `password`) 
VALUES 
('1','111') ,
('2','222')
ON DUPLICATE KEY UPDATE 
`password` = `password`;

更新为字符串password，，即如果原值是0，那么执行后是字符串’password’

INSERT INTO user_admin_t (_id, `password`) 
VALUES 
('1','111') ,
('2','222')
ON DUPLICATE KEY UPDATE 
`password` = 'password';

更新为新insert的值，即如果原值是0，那么执行后是111

INSERT INTO user_admin_t (_id, `password`) 
VALUES 
('1','111') ,
('2','222')
ON DUPLICATE KEY UPDATE 
`password` = VALUES(`password`);

语法报错

INSERT INTO user_admin_t (_id, `password`) 
VALUES 
('1','111') ,
('2','222')
ON DUPLICATE KEY UPDATE 
`password` = VALUES('password');