Ubuntu 20.04修改Mysql默认安装密码

通常做法

>use mysql; 
>flush privileges; 
>alter user 'root'@'localhost' identified by '123456'; 
>flush privileges quit

错误处理

如果在直接执行上述命令后不生效，或者alter user 'root'@'localhost' identified by '123456';会报错：ERROR 1819 (HY000): Your password does not satisfy the current policy requirements，这是密码设置太简单而不符合新版本MySQL的密码策略要求，如果想要使用简单密码，需要进行以下设置：

>use mysql; 
>flush privileges; 
>SHOW VARIABLES LIKE 'validate_password%'; 
>set global validate_password.policy=0; 
>set global validate_password.special_char_count=0; 
>set global validate_password.length=6; 
>set global validate_password.mixed_case_count=0; 
>SHOW VARIABLES LIKE 'validate_password%'; 
>ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456'; 
>flush privileges; 
>quit
sudo service mysql restart;