MySQL 5.7的角色功能：

创建用户并授予用户角色功能：

mysql> create user 'junior'@'127.0.0.1' identified by '123';

Query OK, 0 rows affected (0.01 sec)

mysql> create user 'tom'@'127.0.0.1' identified by '123';

Query OK, 0 rows affected (0.00 sec)

mysql> create user 'jim'@'127.0.0.1' identified by '123';

Query OK, 0 rows affected (0.01 sec)

mysql> grant proxy on 'junior'@'127.0.0.1' to 'tom'@'127.0.0.1';

Query OK, 0 rows affected (0.01 sec)

mysql> grant proxy on 'junior'@'127.0.0.1' to 'jim'@'127.0.0.1';

Query OK, 0 rows affected (0.00 sec)

mysql> grant select on *.* to 'junior'@'127.0.0.1';

Query OK, 0 rows affected (0.00 sec)

mysql> show grants for 'junior'@'127.0.0.1';

+---------------------------------------------+

| Grants for junior@127.0.0.1|

+---------------------------------------------+

| GRANT SELECT ON *.* TO 'junior'@'127.0.0.1' |

+---------------------------------------------+

1 row in set (0.00 sec)

mysql> show grants for 'jim'@'127.0.0.1';

+----------------------------------------------------------+

| Grants for jim@127.0.0.1|

+----------------------------------------------------------+

| GRANT USAGE ON *.* TO 'jim'@'127.0.0.1' |

| GRANT PROXY ON 'junior'@'127.0.0.1' TO 'jim'@'127.0.0.1' |

+----------------------------------------------------------+

2 rows in set (0.00 sec)

mysql> show grants for 'tom'@'127.0.0.1';

+----------------------------------------------------------+

| Grants for tom@127.0.0.1|

+----------------------------------------------------------+

| GRANT USAGE ON *.* TO 'tom'@'127.0.0.1' |

| GRANT PROXY ON 'junior'@'127.0.0.1' TO 'tom'@'127.0.0.1' |

+----------------------------------------------------------+

2 rows in set (0.00 sec)

mysql> use mysql;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select * from proxies_priv;

+-----------+------+--------------+--------------+------------+----------------------+---------------------+

| Host | User | Proxied_host | Proxied_user | With_grant | Grantor | Timestamp |

+-----------+------+--------------+--------------+------------+----------------------+---------------------+

| localhost | root | | | 1 | boot@connecting host | 0000-00-00 00:00:00 |

| 127.0.0.1 | tom | 127.0.0.1| junior | 0 | root@localhost | 0000-00-00 00:00:00 |

| 127.0.0.1 | jim | 127.0.0.1| junior | 0 | root@localhost | 0000-00-00 00:00:00 |

+-----------+------+--------------+--------------+------------+----------------------+---------------------+

3 rows in set (0.00 sec)