【MySQL 13】安装MySQL后第一次修改密码，可以可跳过MySQL密码验证进行登录

 vi/etc/my.cnf
      在my.cnf文件中添加代码skip-grant-tables（即：可跳过MySQL密码验证进行登录）

	  systemctl restart mysqld

无需使用密码，可直接登录MySQL

[root@localhost /]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 7
Server version: 8.0.18 MySQL Community Server - GPL

Copyright (c) 2000, 2019, 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.

	  <1>先将原本的密码设置为空
	  mysql>update user set authentication_string="" where user='root';
	  <2>之后在在my.cnf文件中删除skip-grant-tables，之后再次进入mysql
	  <3>mysql>ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '密码‘；

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> update user set authentication_string="" where user='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> exit
Bye

[root@localhost /]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 30
Server version: 8.0.18

Copyright (c) 2000, 2019, 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> use mysql;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'siteweb1!';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

mysql> set global validate_password.policy=0;
Query OK, 0 rows affected (0.00 sec)

mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'siteweb1!';
Query OK, 0 rows affected (0.00 sec)

mysql> exit
Bye

	  flush privileges;

去掉my.cnf文件中添加代码skip-grant-tables

 systemctl restart mysqld