create role r1;
grant r1 to root@localhost;
create user u1;
set role r1;
grant r1 to u1;
select * from mysql.roles_mapping;
Host	User	Role	Admin_option
%	u1	r1	N
localhost	root	r1	Y
drop user u1;
select * from mysql.roles_mapping;
Host	User	Role	Admin_option
localhost	root	r1	Y
show grants;
Grants for root@localhost
GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION
GRANT PROXY ON ''@'%' TO 'root'@'localhost' WITH GRANT OPTION
GRANT USAGE ON *.* TO 'r1'
GRANT r1 TO 'root'@'localhost' WITH ADMIN OPTION
drop role r1;
select * from mysql.roles_mapping;
Host	User	Role	Admin_option
show grants;
Grants for root@localhost
GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION
GRANT PROXY ON ''@'%' TO 'root'@'localhost' WITH GRANT OPTION