【MySQL】用户管理

13.用户管理

13.1用户

13.1.1用户信息

MySQL 中的用户，都存储在系统数据库 mysql 的 user 表中。

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mysql> use mysql;
Database changed
mysql> select host,user,authentication_string from user;
+-----------+---------------+-------------------------------------------+
| host      | user          | authentication_string                     |
+-----------+---------------+-------------------------------------------+
| localhost | root          | *81F5E21E35407D884A6CD4A731AEBF6AF209E1B |
| localhost | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | mysql.sys     | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+-----------+---------------+-------------------------------------------+

可以通过 desc user 初步查看一下表结构

字段解释：

host：表示这个用户可以从哪个主机登陆，如果是 localhost，表示只能从本机登陆。
user：用户名。
authentication_string：用户密码通过 password 函数加密后的。
*\ _ priv：用户拥有的权限。

13.1.2 创建用户

语法：

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create user '用户名'@'登陆主机/ip' identified by '密码';

案例：

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mysql> create user 'xixi'@'localhost' identified by '12345678';
Query OK, 0 rows affected (0.06 sec)

mysql> select user,host,authentication_string from user;
+---------------+-----------+-------------------------------------------+
| user          | host      | authentication_string                     |
+---------------+-----------+-------------------------------------------+
| root          | %         | *A2F7C9D334175DE9AF4DB4F5473E0BD0F5FA9E75 |
| mysql.session | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| mysql.sys     | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| whb           | localhost | *84AAC12F54AB666ECFC2A83C676908C8BBC381B1 | -- 新增用户
+---------------+-----------+-------------------------------------------+
4 rows in set (0.00 sec)
-- 此时便可以使用新账号新密码进行登陆啦

备注：

可能实际在设置密码的时候，因为 mysql 本身的认证等级比较高，一些简单的密码无法设置，会爆出如下报错：

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ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

解决方案：
关于新增用户这里，需要大家注意，不要轻易添加一个可以从任意地方登陆的 user。

13.1.3 删除用户

语法：

sql 复制代码

drop user '用户名'@'主机名'

示例：

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mysql> select user,host,authentication_string from user;
+---------------+-----------+-------------------------------------------+
| user          | host      | authentication_string                     |
+---------------+-----------+-------------------------------------------+
| root          | %         | *A2F7C9D334175DE9AF4DB4F5473E0BD0F5FA9E75 |
| mysql.session | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| mysql.sys     | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| xixi           | localhost | *84AAC12F54AB666ECFC2A83C676908C8BBC381B1 |
+---------------+-----------+-------------------------------------------+
4 rows in set (0.00 sec)

mysql> drop user xixi; -- 尝试删除
ERROR 1396 (HY000): Operation DROP USER failed for 'whb'@'%' -- <= 直接给个用户名，不能删除，它默认是%，表示所有地方可以登陆的用户

mysql> drop user 'xixi'@'localhost'; -- 删除用户
Query OK, 0 rows affected (0.00 sec)

mysql> select user,host,authentication_string from user;
+---------------+-----------+-------------------------------------------+
| user          | host      | authentication_string                     |
+---------------+-----------+-------------------------------------------+
| root          | %         | *A2F7C9D334175DE9AF4DB4F5473E0BD0F5FA9E75 |
| mysql.session | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| mysql.sys     | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+---------------+-----------+-------------------------------------------+
3 rows in set (0.00 sec)

13.1.4 修改用户密码

语法：

自己改自己密码

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set password=password('新的密码');

root 用户修改指定用户的密码

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set password for '用户名'@'主机名'=password('新的密码');

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mysql> select host,user, authentication_string from user;
+-----------+---------------+-------------------------------------------+
| host      | user          | authentication_string                     |
+-----------+---------------+-------------------------------------------+
| %         | root          | *A2F7C9D334175DE9AF4DB4F5473E0BD0F5FA9E75 |
| localhost | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | mysql.sys     | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | xixi           | *84AAC12F54AB666ECFC2A83C676908C8BBC381B1 |
+-----------+---------------+-------------------------------------------+
4 rows in set (0.00 sec)

mysql> set password for 'xixi'@'localhost'=password('87654321');
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select host,user, authentication_string from user;
+-----------+---------------+-------------------------------------------+
| host      | user          | authentication_string                     |
+-----------+---------------+-------------------------------------------+
| %         | root          | *A2F7C9D334175DE9AF4DB4F5473E0BD0F5FA9E75 |
| localhost | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | mysql.sys     | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | xixi           | *5D24C4D94238E65A6407DFAB95AA4AE97CA2B199 |
+-----------+---------------+-------------------------------------------+
4 rows in set (0.00 sec)

13.2 数据库的权限

MySQL 数据库提供的权限列表：

权限	列	上下文
CREATE	Create_priv	数据库、表或索引
DROP	Drop_priv	数据库或表
GRANT OPTION	Grant_priv	数据库、表或保存的程序
REFERENCES	References_priv	数据库或表
ALTER	Alter_priv	表
DELETE	Delete_priv	表
INDEX	Index_priv	表
INSERT	Insert_priv	表
UPDATE	Update_priv	表
CREATE VIEW	Create_view_priv	视图
SHOW VIEW	Show_view_priv	视图
ALTER ROUTINE	Alter_routine_priv	保存的程序
CREATE ROUTINE	Create_routine_priv	保存的程序
EXECUTE	Execute_priv	保存的程序
FILE	File_priv	服务器主机上的文件访问
CREATE TEMPORARY TABLES	Create_tmp_table_priv	服务器管理
LOCK TABLES	Lock_tables_priv	服务器管理
CREATE USER	Create_user_priv	服务器管理
PROCESS	Process_priv	服务器管理
RELOAD	Reload_priv	服务器管理
REPLICATION CLIENT	Repl_client_priv	服务器管理
REPLICATION SLAVE	Repl_slave_priv	服务器管理
SHOW DATABASES	Show_db_priv	服务器管理
SHUTDOWN	Shutdown_priv	服务器管理
SUPER	Super_priv	服务器管理

13.2.1 给用户授权

刚创建的用户没有任何权限，需要给用户授权。

语法：

sql 复制代码

grant 权限列表 on 库.对象名 to '用户名'@'登陆位置' [identified by '密码']

说明：
- 权限列表，多个权限用逗号分开
  - grant select on ...
  - grant select, delete, create on ...
  - grant all [privileges] on ... -- 表示赋予该用户在该对象上的所有权限
- *.*：代表本系统中的所有数据库的所有对象（表，视图，存储过程等）
- 库.*：表示某个数据库中的所有数据对象（表，视图，存储过程等）
- identified by可选。如果用户存在，赋予权限的同时修改密码；如果该用户不存在，就是创建用户
案例：

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-- 使用root账号
-- 终端A
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| 57test             |
| bit_index          |
| ccdata_pro         |
| innodbserver       |
| myisam_test        |
| mysql              |
| mysql_sys          |
| performance_schema |
| scott              |
| sys                |
| test               |
| vod_system         |
+--------------------+
14 rows in set (0.00 sec)

mysql> use test;
Database changed
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| account        |
| student        |
| user           |
+----------------+
3 rows in set (0.01 sec)

-- 给用户whb赋予test数据库下所有文件的select权限
mysql> grant select on test.* to 'whb'@'localhost';
Query OK, 0 rows affected (0.01 sec)

-- 使用whb账号
-- 终端B
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)

-- 暂停等root用户给whb赋完权之后，在查看
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| test               | -- 赋完权之后，就能看到新的表
+--------------------+
2 rows in set (0.01 sec)

mysql> use test;
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> show tables;
+----------------+
| Tables_in_test |
+----------------+
| account        |
| student        |
| user           |
+----------------+
3 rows in set (0.00 sec)

mysql> select * from account;
+----+-------+---------+
| id | name  | balance |
+----+-------+---------+
| 2  | 李四  | 321.00  |
| 3  | 王五  | 543.00  |
| 4  | 赵六  | 543.90  |
+----+-------+---------+
4 rows in set (0.00 sec)

-- 没有删除权限
mysql> delete from account;
ERROR 1142 (42000): DELETE command denied to user 'whb'@'localhost' for table 'account'

备注: 特定用户现有查看权限
mysql> show grants for 'whb'@'%';
+-----------------------------------------------------+
| Grants for whb@%                                    |
+-----------------------------------------------------+
| GRANT USAGE ON *.* TO 'whb'@'%'                    |
| GRANT ALL PRIVILEGES ON `whb`.* TO 'whb'@'%'       |
+-----------------------------------------------------+
2 rows in set (0.00 sec)

mysql> show grants for 'root'@'%';
+---------------------------------------------------------------------+
| Grants for root@%                                                   |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION         |
| GRANT PROXY ON ''@'' TO 'root'@'%' WITH GRANT OPTION                |
+---------------------------------------------------------------------+
1 row in set (0.00 sec)

注意: 如果发现赋权限后，没有生效，执行如下指令:
flush privileges;

13.2.2 回收权限

语法：

sql 复制代码

revoke 权限列表 on 库.对象名 from '用户名'@'登陆位置';

示例：

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-- 回收whb对test数据库的所有权限
-- root身份，终端A
mysql> revoke all on test.* from 'whb'@'localhost';
Query OK, 0 rows affected (0.00 sec)

-- whb身份，终端B
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
+--------------------+
2 rows in set (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)