0 rows affected is normal for a successful
GRANT command. Unsuccessful ones will display an error.
If you see
1 warning after
0 rows affected you should type
SHOW WARNINGS; and check whether the warning affects you or not. This one could:
Warning | 1285 | MySQL is started in --skip-name-resolve mode; you must restart it without this switch for this grant to work
SHOW GRANTS command will only show the privileges that the user executing the command has. If you are logged in as
firstname.lastname@example.org then you won't see the grants for
SHOW GRANTS FOR 'root'@'%'; instead.