Mysq数据库相关问题

1.忘记了MySQL的安装目录

进入mysql命令行输入：show variables like "%char%";

结果如下：

mysql> show variables like "%char%";
+--------------------------+---------------------------------------------------------+
| Variable_name | Value |
+--------------------------+---------------------------------------------------------+
| character_set_client | utf8mb4 |
| character_set_connection | utf8mb4 |
| character_set_database | utf8mb4 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | utf8mb4 |
| character_set_system | utf8 |
| character_sets_dir | D:\Program Files\MySQL\MySQL Server 8.0\share\charsets\ |
+--------------------------+---------------------------------------------------------+
8 rows in set, 1 warning (0.00 sec)

mysql>

2.连接mysql时报：message from server: "Host '***.***.***.***' is not allowed to connect to this MySQL server

需改变访问权限

处理方案：

 1、该表法：

操作如下：

1.1 选择要使用的数据库

mysql> use mysql   

1.2 查询

mysql> select host,user from user where user = 'root'; 

1.3 将localhost改成%，或改成固定的ip

mysql> update user set host='%' where user = 'root'; 

1.4 查询

mysql> select host,user from user where user = 'root'; 

1.5 刷新修改权限，使其生效

mysql> flush privileges;  

 

2、授权法：

操作如下：

2.1 选择要使用的数据库

mysql> use mysql    

2.2 更改远程连接设置，'myuser'为用户名，'mypassword'为密码

mysql> GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'%' IDENTIFIED BY 'mypassword' WITH GRANT OPTION;

2.3 刷新修改权限，使其生效

mysql> flush privileges;  

 

3.Windows下使用dos命令进入mysql 

（注意：需配置环境变量）

C:\WINDOWS\system32>net start mysql
请求的服务已经启动。

请键入 NET HELPMSG 2182 以获得更多的帮助。

C:\WINDOWS\system32>d:

D:\>cd D:\Program Files\MySQL\MySQL Server 8.0\bin

D:\Program Files\MySQL\MySQL Server 8.0\bin>mysql -hlocalhost -uroot -p
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
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>

刷新刚才修改的权限，使其生效。