【MySQL的ROLE解決了什么問題】
假設你是一個職業素養良好的DBA比較同時又比較注重權限管理的話；可能遇到過這樣的問題，數據庫中有多個開發人員的賬號；有一天要建
一個新的schema，如果你希望之前所有的賬號都能操作這個schema下的表的話，在mysql-8.0之前你要對第一個賬號都單獨的賦一次權。
mysql-8.0.x所權限抽象了出來用ROLE來表示，當你為ROLE增加新的權限的時候，與這個ROLE關聯的所有用戶的權限也就一并變化了；針對
上面提到的場景在mysql-8.0.x下只要一條SQL就解決了。
【機智的MySQL開發】
MySQL引進ROLE用了一個非常機智的做法，既然ROLE是一堆權限的象征，這東西在MySQL里面本來就有呀！它就是USER呀。
1): 創建角色
查看mysql.user表真會被MySQL的機智給嚇到
select user,host from mysql.user;
+------------------+-----------+
| user | host |
+------------------+-----------+
| devgroup | % |
| backup | 127.0.0.1 |
| mysql.sys | localhost |
| root | localhost |
+------------------+-----------+
說好的role事實上只是一個user呀！
2): 給角色賦權
grant all on tempdb.* to devgroup;
Query OK, 0 rows affected (0.07 sec)
和操作用戶比起來是一樣一樣的！
3):創建用戶并把角色的權限賦給它
create user tom@'127.0.0.1' identified by '123456';
Query OK, 0 rows affected (0.09 sec)
grant devgroup to tom@'127.0.0.1';
Query OK, 0 rows affected (0.09 sec)
4):測試剛創建的用戶是否可以登錄
mysql -h127.0.0.1 -P3306 -utom -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 8.0.13 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show grants;
+-------------------------------------------+
| Grants for tom@127.0.0.1 |
+-------------------------------------------+
| GRANT USAGE ON *.* TO `tom`@`127.0.0.1` |
| GRANT `devgroup`@`%` TO `tom`@`127.0.0.1` |
+-------------------------------------------+
2 rows in set (0.00 sec)
【角色和用戶只是一個硬幣的兩面】
如果你還是覺得“角色”和“用戶”是兩個不一樣的東西、那我只能是出大招了
1): root@127.0.0.1 用戶當成角色賦給剛才的tom用戶
grant root@'127.0.0.1' to tom@'127.0.0.1';
Query OK, 0 rows affected (0.04 sec)
2):用戶tom用戶檢察一下自己的權限
show grants;
+--------------------------------------------------------------+
| Grants for tom@127.0.0.1 |
+--------------------------------------------------------------+
| GRANT USAGE ON *.* TO `tom`@`127.0.0.1` |
| GRANT `devgroup`@`%`,`root`@`127.0.0.1` TO `tom`@`127.0.0.1` |
+--------------------------------------------------------------+
2 rows in set (0.00 sec)
可以看到root@127.0.0.1的權限已經被套上去了、既然都是root用戶的權限了我們來刪除一個tempdb庫看一下吧！
3): 刪庫
drop database tempdb;
ERROR 1044 (42000): Access denied for user 'tom'@'127.0.0.1' to database 'tempdb'
看起來沒有權限刪除這個庫呀！事實上是MySQL-8默認并不會激活role，關于是否激活role是由activate_all_roles_on_login這個參數控制的
4): 開啟activate_all_roles_on_login
set @@global.activate_all_roles_on_login=1;
Query OK, 0 rows affected (0.00 sec)
5): 重新登錄一次tom再試著刪除一下tempdb庫
mysql -h127.0.0.1 -P3306 -utom -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18
Server version: 8.0.13 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> use tempdb;
Database changed
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| tempdb |
+--------------------+
5 rows in set (0.01 sec)
mysql> drop database tempdb;
Query OK, 0 rows affected (0.09 sec)
以上就是詳解MySQL8的新特性ROLE的詳細內容，更多關于MySQL8 新特性ROLE的資料請關注腳本之家其它相關文章！
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