MySQL数据库通常是由总管理员创建不同的管理账户，然后分配不同的权限，把这些账户交给相应的管理人员使用
接下来我将对用户与授权做一些基本的操作
#新建一个名为‘user01’的用户，密码为‘123456',主机名为localhost
mysql> create user 'user01'@'localhost' identified by '123456';
#查看系统用户，创建后的用户是保存在mysql数据库的user表中的，所以在查看用户时要先进mysql这个库
mysql> use mysql;
Database changed
mysql> select user, authentication_string, host from user;
+-----------+-------------------------------------------+-----------+
| user | authentication_string | host |
+-----------+-------------------------------------------+-----------+
| root | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | localhost |
| mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | localhost |
| root | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | % |
| user01 | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | localhost | #可以看到user表中有我刚刚创建的user01用户，且主机名为localhost
+-----------+-------------------------------------------+-----------+
4 rows in set (0.00 sec)
#对用户进行重命名
mysql> rename user 'user01'@'localhost' to 'server01'@'localhost'; #这里我将用户名‘user01’改为‘server01’
Query OK, 0 rows affected (0.00 sec)
mysql> select user, authentication_string, host from user;
+-----------+-------------------------------------------+-----------+
| user | authentication_string | host |
+-----------+-------------------------------------------+-----------+
| root | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | localhost |
| mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | localhost |
| root | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | % |
| server01 | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | host | #再次进行查看，可以看到用户名已经改变
+-----------+-------------------------------------------+-----------+
4 rows in set (0.00 sec)
#修改用户密码
（1）修改当前用户的密码
mysql> set password = password('123123'); #使用该命令将密码改为‘123123’
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> quit;
Bye
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g. #登入成功
（2）修改其他用户的密码
mysql> set password for 'server01'@'localhost' = password('123123'); #将server01用户密码改为123123
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> quit;
Bye
[root@localhost ~]# mysql -u server01 -p #用新密码进行登录
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
#忘记root密码的解决办法
（1）关闭数据库，进主配置文件
[root@localhost ~]# systemctl stop mysqld.service
[root@localhost ~]# vim /etc/my.cnf
（2）对主配置文件进行更改
[mysqld]
user = mysql
basedir = /usr/local/mysql
datadir = /usr/local/mysql/data
port = 3306
character_set_server=utf8
pid-file = /usr/local/mysql/mysqld.pid
socket = /usr/local/mysql/mysql.sock
server-id = 1
skip-grant-tables #加入这条语句，作用是登录数据库不需要密码
（3）重启数据库，直接登录
[root@localhost ~]# systemctl restart mysqld.service
[root@localhost ~]# mysql -uroot
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.17 Source distribution
Copyright (c) 2000, 2016, 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>
（4）使用update修改root密码
mysql> update mysql.user set authentication_string=password('abc123') where user='root'; #将密码修改为‘abc123’
Query OK, 2 rows affected, 1 warning (0.00 sec)
Rows matched: 2 Changed: 2 Warnings: 1
mysql> quit;
Bye
[root@localhost ~]# vim /etc/my.cnf #进入主配置文件
#skip-grant-tables #注释掉前面加的这条语句，一定要注释掉这条命令
[root@localhost ~]# systemctl restart mysqld.service #重启mysql服务
[root@localhost ~]# mysql -uroot -p #使用新密码登录
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.17 Source distribution
Copyright (c) 2000, 2016, 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> #登录成功
#删除用户
mysql> drop user 'server01'@'localhost';
#给用户授权 grant 权限列表 on 库名.表名 to 用户名@主机名 [identified by '密码']
mysql> grant all on mysql.user to 'tom'@'localhost' identified by '123456'; #all表示所有的权限都给tom这个用户，这里也可以更某一个权限，这条命令的用法有很多，如果用户列表中没有tom这个用户，便会自动创建，带有创建用户的功能，如果有这个用户，那指定的密码会覆盖原有的密码，带有更改用户密码的功能
Query OK, 0 rows affected, 1 warning (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 user, authentication_string, host from user;
+-----------+-------------------------------------------+-----------+
| user | authentication_string | host |
+-----------+-------------------------------------------+-----------+
| root | *6691484EA6B50DDDE1926A220DA01FA9E575C18A | localhost |
| mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | localhost |
| root | *6691484EA6B50DDDE1926A220DA01FA9E575C18A | % |
| tom | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | localhost |
+-----------+-------------------------------------------+-----------+
4 rows in set (0.00 sec)
#查看权限 show grants for 'username'@'主机名';
mysql> show grants for tom@localhost; #查看tom的权限
+-------------------------------------------------------------+
| Grants for tom@localhost |
+-------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'tom'@'localhost' |
| GRANT ALL PRIVILEGES ON "mysql"."user" TO 'tom'@'localhost' |
+-------------------------------------------------------------+
2 rows in set (0.00 sec)
#撤销用户权限 revoke 权限列表 on 数据库名.表名 from '用户名'@'主机名';
mysql> revoke drop on mysql.user from 'tom'@'localhost'; #撤销tom的drop权限
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for 'tom'@'localhost'; #查看tom权限
+------------------------------------------------------------------------------------------------------------------------------------------------+
| Grants for tom@localhost |
+------------------------------------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'tom'@'localhost' |
| GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, REFERENCES, INDEX, ALTER, CREATE VIEW, SHOW VIEW, TRIGGER ON "mysql"."user" TO 'tom'@'localhost' | #可以看到这里已经没有drop权限了
+------------------------------------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)