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MySQL快速入门——用户管理

news 2025/11/13 7:27:04

MySQL快速入门——用户管理

1. 用户
- 1.1 用户信息
- 1.2 创建用户
- 1.3 删除用户
- 1.4 修改用户密码
2. 数据库的权限
- 2.1 给用户授权
- 2.2 回收权限

1. 用户

如果我们只能使用root用户，这样存在安全隐患。这时，就需要使用MySQL的用户管理。

在这里插入图片描述

1.1 用户信息

1. MySQL中的用户，都存储在系统数据库mysql的user表中

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 -ADatabase changed
mysql> select host,user,authentication_string from user;
+-----------+------------------+------------------------------------------------------------------------+
| host      | user             | authentication_string                                                  |
+-----------+------------------+------------------------------------------------------------------------+
| %         | root             | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| localhost | mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | root             | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+-----------+------------------+------------------------------------------------------------------------+
5 rows in set (0.01 sec)

2. 可以通过desc初步查看一下表的结构：

可以看到结构是相当复杂的，有很多字段。在上面的例子中，我们只是将最常用的字段展示出来了，即主机host，用户名user，密码authentication_string。

mysql> desc user;
+--------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Field                    | Type                              | Null | Key | Default               | Extra |
+--------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Host                     | char(255)                         | NO   | PRI |                       |       |
| User                     | char(32)                          | NO   | PRI |                       |       |
| Select_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Insert_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Update_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Delete_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Create_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Drop_priv                | enum('N','Y')                     | NO   |     | N                     |       |
| Reload_priv              | enum('N','Y')                     | NO   |     | N                     |       |
| Shutdown_priv            | enum('N','Y')                     | NO   |     | N                     |       |
| Process_priv             | enum('N','Y')                     | NO   |     | N                     |       |
| File_priv                | enum('N','Y')                     | NO   |     | N                     |       |
| Grant_priv               | enum('N','Y')                     | NO   |     | N                     |       |
| References_priv          | enum('N','Y')                     | NO   |     | N                     |       |
| Index_priv               | enum('N','Y')                     | NO   |     | N                     |       |
| Alter_priv               | enum('N','Y')                     | NO   |     | N                     |       |
| Show_db_priv             | enum('N','Y')                     | NO   |     | N                     |       |
| Super_priv               | enum('N','Y')                     | NO   |     | N                     |       |
| Create_tmp_table_priv    | enum('N','Y')                     | NO   |     | N                     |       |
| Lock_tables_priv         | enum('N','Y')                     | NO   |     | N                     |       |
| Execute_priv             | enum('N','Y')                     | NO   |     | N                     |       |
| Repl_slave_priv          | enum('N','Y')                     | NO   |     | N                     |       |
| Repl_client_priv         | enum('N','Y')                     | NO   |     | N                     |       |
| Create_view_priv         | enum('N','Y')                     | NO   |     | N                     |       |
| Show_view_priv           | enum('N','Y')                     | NO   |     | N                     |       |
| Create_routine_priv      | enum('N','Y')                     | NO   |     | N                     |       |
| Alter_routine_priv       | enum('N','Y')                     | NO   |     | N                     |       |
| Create_user_priv         | enum('N','Y')                     | NO   |     | N                     |       |
| Event_priv               | enum('N','Y')                     | NO   |     | N                     |       |
| Trigger_priv             | enum('N','Y')                     | NO   |     | N                     |       |
| Create_tablespace_priv   | enum('N','Y')                     | NO   |     | N                     |       |
| ssl_type                 | enum('','ANY','X509','SPECIFIED') | NO   |     |                       |       |
| ssl_cipher               | blob                              | NO   |     | NULL                  |       |
| x509_issuer              | blob                              | NO   |     | NULL                  |       |
| x509_subject             | blob                              | NO   |     | NULL                  |       |
| max_questions            | int unsigned                      | NO   |     | 0                     |       |
| max_updates              | int unsigned                      | NO   |     | 0                     |       |
| max_connections          | int unsigned                      | NO   |     | 0                     |       |
| max_user_connections     | int unsigned                      | NO   |     | 0                     |       |
| plugin                   | char(64)                          | NO   |     | caching_sha2_password |       |
| authentication_string    | text                              | YES  |     | NULL                  |       |
| password_expired         | enum('N','Y')                     | NO   |     | N                     |       |
| password_last_changed    | timestamp                         | YES  |     | NULL                  |       |
| password_lifetime        | smallint unsigned                 | YES  |     | NULL                  |       |
| account_locked           | enum('N','Y')                     | NO   |     | N                     |       |
| Create_role_priv         | enum('N','Y')                     | NO   |     | N                     |       |
| Drop_role_priv           | enum('N','Y')                     | NO   |     | N                     |       |
| Password_reuse_history   | smallint unsigned                 | YES  |     | NULL                  |       |
| Password_reuse_time      | smallint unsigned                 | YES  |     | NULL                  |       |
| Password_require_current | enum('N','Y')                     | YES  |     | NULL                  |       |
| User_attributes          | json                              | YES  |     | NULL                  |       |
+--------------------------+-----------------------------------+------+-----+-----------------------+-------+
51 rows in set (0.01 sec)

3. 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。%表示可以从任意远端主机登入；
user：用户名；
authentication_string：用户密码通过caching_sha2_password函数加密后的（MySQL5.7及之前，采用password函数加密）；
*_priv：用户拥有的权限。

在生产环境下，root用户强烈不建议设置host为%，不安全。其实MySQL一般都是在公司内网使用，都不会将端口号暴漏在公网上。

1.2 创建用户

1. 语法：

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

2. 案例：

mysql> create user 'lhy'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.02 sec)mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| lhy              | localhost | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9                              |	-- 新增用户
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
6 rows in set (0.00 sec)

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。

1.3 删除用户

1. 语法

drop user '用户名'@'主机名';

2. 案例

mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| lhy              | localhost | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9                              |
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
6 rows in set (0.00 sec)mysql>  drop user lhy;	-- 尝试删除
ERROR 1396 (HY000): Operation DROP USER failed for 'lhy'@'%' 
-- 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 'lhy'@'localhost'; 
Query OK, 0 rows affected (0.01 sec)mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
5 rows in set (0.01 sec)

删除用户本质上就是删除user表中的一行记录，完全可以使用delete操作，只不过mysql专门设置了另一套sql又封装了一下；创建用户亦是如此，如果使用insert into插入数据，岂不是要插入那么多列信息？太麻烦了。

1.4 修改用户密码

1. 语法：

自己改自己密码：

set password=password('新的密码'); -- MySQL5.7及之前
set password='新密码';	-- MySQL8.0及以后，会自动加密

root用户修改指定用户的密码：

set password for '用户名'@'主机名'=password('新的密码'); -- MySQL5.7即之前
set password for '用户名'@'主机名'='新密码';		-- MySQL8.0及以后，自动加密

通用写法：

alter user '用户名'@'主机名' identified by 'new_password';	-- MySQL8.0及以后

2. 案例（root用户修改其他用户密码）

mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| lhy              | localhost | *AA1420F182E88B9E5F874F6FBE7459291E8F4601                              |	-- 旧密码
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
6 rows in set (0.00 sec)mysql> set password for 'lhy'@'localhost' = '654321';
Query OK, 0 rows affected (0.01 sec)mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| lhy              | localhost | *2A032F7C5BA932872F0F045E0CF6B53CF702F2C5                              | -- 密码改变
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
6 rows in set (0.00 sec)

2. 数据库的权限

MySQL数据库提供的权限列表：

在这里插入图片描述

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。

1. 语法

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

2. 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。

3. 案例

使用root用户，创建一个新用户new（终端A）：

mysql> create user 'new'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.01 sec)mysql> select user,host,authentication_string from user;
+------------------+-----------+------------------------------------------------------------------------+
| user             | host      | authentication_string                                                  |
+------------------+-----------+------------------------------------------------------------------------+
| root             | %         | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
| lhy              | localhost | *2A032F7C5BA932872F0F045E0CF6B53CF702F2C5                              |
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.session    | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| mysql.sys        | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| new              | localhost | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9                              |
| root             | localhost | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B                              |
+------------------+-----------+------------------------------------------------------------------------+
7 rows in set (0.00 sec)

使用来自oracle 9i的经典测试表中数据测试：

mysql> use scott;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
mysql> show tables;
+-----------------+
| Tables_in_scott |
+-----------------+
| dept            |
| emp             |
| salgrade        |
+-----------------+
5 rows in set (0.00 sec)

新启一个终端，使用new用户连接，试试看能不能访问这个库和这个表（终端B）：

(base) ubuntu@Ubuntu22:~$ mysql -unew -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.43 MySQL Community Server - GPLCopyright (c) 2000, 2025, Oracle and/or its affiliates.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 databases;	-- 发现新用户几乎什么权限没有，什么库都看不到
+--------------------+
| Database           |
+--------------------+
| information_schema |
| performance_schema |
+--------------------+
2 rows in set (0.02 sec)

回到终端A，用root给用户new赋予scott数据库下所有文件的select权限（终端A）：

mysql> grant select on scott.* to 'new'@'localhost';
Query OK, 0 rows affected (0.01 sec)

到终端B，看看现在new用户能访问scott库了吗（终端B）：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| performance_schema |
| scott              |		-- 可以看到 scott 库了
+--------------------+
3 rows in set (0.00 sec)mysql> use scott;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
mysql> show tables;
+-----------------+
| Tables_in_scott |
+-----------------+
| dept            |
| emp             |
| salgrade        |
+-----------------+
3 rows in set (0.00 sec)mysql> select * from emp;	-- 有select权限
+--------+--------+-----------+------+---------------------+---------+---------+--------+
| empno  | ename  | job       | mgr  | hiredate            | sal     | comm    | deptno |
+--------+--------+-----------+------+---------------------+---------+---------+--------+
| 007369 | SMITH  | CLERK     | 7902 | 1980-12-17 00:00:00 |  800.00 |    NULL |     20 |
| 007499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 00:00:00 | 1600.00 |  300.00 |     30 |
| 007521 | WARD   | SALESMAN  | 7698 | 1981-02-22 00:00:00 | 1250.00 |  500.00 |     30 |
| 007566 | JONES  | MANAGER   | 7839 | 1981-04-02 00:00:00 | 2975.00 |    NULL |     20 |
| 007654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 |     30 |
| 007698 | BLAKE  | MANAGER   | 7839 | 1981-05-01 00:00:00 | 2850.00 |    NULL |     30 |
| 007782 | CLARK  | MANAGER   | 7839 | 1981-06-09 00:00:00 | 2450.00 |    NULL |     10 |
| 007788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 00:00:00 | 3000.00 |    NULL |     20 |
| 007839 | KING   | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 |    NULL |     10 |
| 007844 | TURNER | SALESMAN  | 7698 | 1981-09-08 00:00:00 | 1500.00 |    0.00 |     30 |
| 007876 | ADAMS  | CLERK     | 7788 | 1987-05-23 00:00:00 | 1100.00 |    NULL |     20 |
| 007900 | JAMES  | CLERK     | 7698 | 1981-12-03 00:00:00 |  950.00 |    NULL |     10 |
| 007902 | FORD   | ANALYST   | 7566 | 1981-12-03 00:00:00 | 3000.00 |    NULL |     20 |
| 007934 | MILLER | CLERK     | 7782 | 1982-01-23 00:00:00 | 1300.00 |    NULL |     10 |
+--------+--------+-----------+------+---------------------+---------+---------+--------+
14 rows in set (0.01 sec)

试试有其他权限吗（终端B）：

mysql> select * from emp;
+--------+--------+-----------+------+---------------------+---------+---------+--------+
| empno  | ename  | job       | mgr  | hiredate            | sal     | comm    | deptno |
+--------+--------+-----------+------+---------------------+---------+---------+--------+
| 007369 | SMITH  | CLERK     | 7902 | 1980-12-17 00:00:00 |  800.00 |    NULL |     20 |
| 007499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 00:00:00 | 1600.00 |  300.00 |     30 |
| 007521 | WARD   | SALESMAN  | 7698 | 1981-02-22 00:00:00 | 1250.00 |  500.00 |     30 |
| 007566 | JONES  | MANAGER   | 7839 | 1981-04-02 00:00:00 | 2975.00 |    NULL |     20 |
| 007654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 |     30 |
| 007698 | BLAKE  | MANAGER   | 7839 | 1981-05-01 00:00:00 | 2850.00 |    NULL |     30 |
| 007782 | CLARK  | MANAGER   | 7839 | 1981-06-09 00:00:00 | 2450.00 |    NULL |     10 |
| 007788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 00:00:00 | 3000.00 |    NULL |     20 |
| 007839 | KING   | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 |    NULL |     10 |
| 007844 | TURNER | SALESMAN  | 7698 | 1981-09-08 00:00:00 | 1500.00 |    0.00 |     30 |
| 007876 | ADAMS  | CLERK     | 7788 | 1987-05-23 00:00:00 | 1100.00 |    NULL |     20 |
| 007900 | JAMES  | CLERK     | 7698 | 1981-12-03 00:00:00 |  950.00 |    NULL |     10 |
| 007902 | FORD   | ANALYST   | 7566 | 1981-12-03 00:00:00 | 3000.00 |    NULL |     20 |
| 007934 | MILLER | CLERK     | 7782 | 1982-01-23 00:00:00 | 1300.00 |    NULL |     10 |
+--------+--------+-----------+------+---------------------+---------+---------+--------+
14 rows in set (0.00 sec)mysql> delete from emp where empno=7369;		-- 很显然，sql被拒绝了
ERROR 1142 (42000): DELETE command denied to user 'new'@'localhost' for table 'emp'

4. 特定用户现有查看权限

非root用户，只能查看自己的权限：

mysql> show grants for 'new'@'localhost';
+------------------------------------------------+
| Grants for new@localhost                       |
+------------------------------------------------+
| GRANT USAGE ON *.* TO `new`@`localhost`        |
| GRANT SELECT ON `scott`.* TO `new`@`localhost` |	-- 对scott库中所有表*有select权限
+------------------------------------------------+
2 rows in set (0.00 sec)

5. 赋权后不生效？

这是因为赋权操作将权限写入磁盘后，并没有加载进缓存中，所以需要刷新：

flush privileges;

2.2 回收权限

1. 语法：

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

2. 案例

-- 终端A
mysql> revoke all on scott.* from 'new'@'localhost';
Query OK, 0 rows affected (0.01 sec)-- 终端B
mysql> select user();
+---------------+
| user()        |
+---------------+
| new@localhost |
+---------------+
1 row in set (0.00 sec)mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| performance_schema |
+--------------------+
2 rows in set (0.00 sec)