insert into mysql.user(Host,User,Password) values("localhost","u",password("123"));

flush privileges;

grant all privileges on uDB.* to u@localhost identified by '123';

flush privileges;

grant select,update on uDB.* to u@localhost identified by '123';

flush privileges;

DELETE FROM user WHERE User="u" and Host="localhost";

flush privileges;

update mysql.user set host = '%' where user = 'u';

grant all privileges on *.* to 'u'@'%' identified by '123'

revoke privileges on dbname[.tbname] from username;