Mysql的用户基本操作

创建用户：

mysql> create user 'cai'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from mysql.user;                                                            
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| cai           | localhost |
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
| wordpress     | localhost |
+---------------+-----------+
5 rows in set (0.00 sec)

[root@cairui ~]# mysql -ucai -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 275
Server version: 5.7.21-debug Source distribution

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.

授权：

命令：GRANT privileges ON databasename.tablename TO 'username'@'host'

mysql> grant select,delete,create,insert,update on aa.* to 'cai'@'localhost';
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for cai@localhost;
+-----------------------------------------------------------------------------+
| Grants for cai@localhost                                                    |
+-----------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'cai'@'localhost'                                     |
| GRANT SELECT, INSERT, UPDATE, DELETE, CREATE ON `aa`.* TO 'cai'@'localhost' |
+-----------------------------------------------------------------------------+
2 rows in set (0.00 sec)

撤销用户权限：

命令：REVOKE privilege ON databasename.tablename FROM 'username'@'host';

mysql> show grants for cai@localhost;
+-----------------------------------------------------------------------------+
| Grants for cai@localhost                                                    |
+-----------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'cai'@'localhost'                                     |
| GRANT SELECT, INSERT, UPDATE, DELETE, CREATE ON `aa`.* TO 'cai'@'localhost' |
+-----------------------------------------------------------------------------+
2 rows in set (0.00 sec)

mysql> revoke insert on aa.* from 'cai'@'localhost';
Query OK, 0 rows affected (0.00 sec)

mysql> show grants for cai@localhost;
+---------------------------------------------------------------------+
| Grants for cai@localhost                                            |
+---------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'cai'@'localhost'                             |
| GRANT SELECT, UPDATE, DELETE, CREATE ON `aa`.* TO 'cai'@'localhost' |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)　

设置与修改用户密码：

　　方法一：

[root@cairui ~]# mysqladmin -ucai -p'123456' password '123'
mysqladmin: [Warning] Using a password on the command line interface can be insecure.
Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.
[root@cairui ~]# mysql -ucai -p123
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 279
Server version: 5.7.21-debug Source distribution

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.

　　方法二：

mysql> update mysql.user set authentication_string=password('cai') where user='cai' ;
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1
mysql> flush privileges;
[root@cairui ~]# mysql -ucai -pcai;
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 284
Server version: 5.7.21-debug Source distribution

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.

　  方法三：

mysql> set password=password('root');
Query OK, 0 rows affected, 1 warning (0.00 sec)
[root@cairui ~]# mysql -uroot -proot
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 288
Server version: 5.7.21-debug Source distribution

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> 

忘记密码情况下的登录：

[root@cairui mysql]# bin/mysqld_safe --skip-grant-tables & 
#登录时不需要密码，进入可修改密码

删除用户：

mysql> select user,host from mysql.user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| cai           | localhost |
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
| wordpress     | localhost |
+---------------+-----------+
5 rows in set (0.00 sec)

mysql> drop user 'cai'@'localhost';
Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from mysql.user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
| wordpress     | localhost |
+---------------+-----------+
4 rows in set (0.00 sec)