MySQL的skip-grant-tables
MySQL在Windows、Linux平台的安装，可以参考，
《Windows环境安装MySQL ZIP Archive》
Windows下安装的MySQL 5.7，可以用如下指令，进行初始化、服务注册、启动服务，
C:\bisal\mysql\bin>mysqld --initialize --user=mysql --console
2021-01-12T11:46:53.608737Z 0 [Warning] InnoDB: New log files created, LSN=45790
2021-01-12T11:46:53.889730Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2021-01-12T11:46:53.981412Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: ddb683f6-54cb-11eb-ac61-0250f2000002.
2021-01-12T11:46:53.996569Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2021-01-12T11:46:56.054507Z 0 [Warning] CA certificate ca.pem is self signed.
2021-01-12T11:46:56.563731Z 1 [Note] A temporary password is generated for root@localhost: Bgbo>f4-Uv1j
C:\bisal\mysql\bin>mysqld install
Service successfully installed.
C:\bisal\mysql\bin>net start mysql
MySQL 服务正在启动 .
MySQL 服务已经启动成功。此时data路径下，就会出现这些数据文件，
看到一些教程，说在首次配置时，可以在配置文件my.ini中设置skip-grant-tables参数，
skip-grant-tables顾名思义，该命令作用是跳过授权表，就是说谁都能进入MySQL看到所有数据表，输入任意字符账号密码都可以，当忘记账号密码时可以使用改命令修改密码，但是要随用随关，重启mysql，不然服务器上会有很大的风险。
输入登陆的指令，但是可任意输入密码，都可以登录，
C:\bisal\mysql\bin>mysql -u root -p
Enter password: ******
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.32 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>查看用户，显示的是skip-grants user，说明确实skip-grants参数起了作用，
mysql> select current_user;
+-----------------------------------+
| current_user |
+-----------------------------------+
| skip-grants user@skip-grants host |
+-----------------------------------+
1 row in set (0.00 sec)登陆后，可以update更新root的密码，注意5.7的user存储密码的字段名称是authentication_string，
mysql> update mysql.user set authentication_string=password('mysql') where user='root' and host='localhost';
Query OK, 1 row affected, 1 warning (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 1密码用password函数，进行了加密，
mysql> select password('mysql') from dual;
+-------------------------------------------+
| password('mysql') |
+-------------------------------------------+
| *E74858DB86EBA20BC33D0AECAE8A8108C56B17FA |
+-------------------------------------------+
1 row in set, 1 warning (0.00 sec)
mysql> select host, user, authentication_string from user;
+-----------+---------------+-------------------------------------------+
| host | user | authentication_string |
+-----------+---------------+-------------------------------------------+
| localhost | root | *E74858DB86EBA20BC33D0AECAE8A8108C56B17FA |
| localhost | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+-----------+---------------+-------------------------------------------+
3 rows in set (0.00 sec)当前模式下，而且支持用mysql直接进行登录，
C:\bisal\mysql\bin>mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.32 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>但是这种跳过授权表的操作，毕竟不安全，相当于开了后门，现在将skip-grant-tables注释，
# skip-grant-tables然后在Windows的服务窗口重启MySQL服务，cmd-services.msc，
此时使用mysql，会提示1045，
C:\bisal\mysql\bin>mysql
ERROR 1045 (28000): Access denied for user 'ODBC'@'localhost' (using password: NO)用mysql -u -root -p登录，同样提示1045的错误，
C:\bisal\mysql\bin>mysql -u -root -p
Enter password: ************
ERROR 1045 (28000): Access denied for user '-root'@'localhost' (using password: YES)可以指定-h登录，
C:\bisal\mysql\bin>mysql -u root -h localhost -p
Enter password: *****
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.32 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>他会提示使用ALTER USRE重置密码，
mysql> use mysql
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> alter user 'root'@'localhost' identified by 'mysql' password expire never;
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)此时登陆的用户，不再是skip-grants，
mysql> select current_user;
+----------------+
| current_user |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)MySQL我算小白，但是发现其实一些很小的知识点，例如登录，还是蕴涵了很多的原理，理解他的原理，多多实践，可能才会更深入的了解MySQL，当然这个过程，可能是很艰辛，还是要量变引起质变，各位共勉了。
参考，
https://blog.csdn.net/ibsfn/article/details/88963040
https://www.cnblogs.com/zhoushiya/p/12107201.html
https://www.cnblogs.com/jet-angle/p/11906671.html
本文参与 腾讯云自媒体同步曝光计划，分享自作者个人站点/博客。
原始发表：2021/01/13 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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