1.從debian.cnf中找到安裝時生成的使用者名稱和密碼

(base) yhq@yhq-System-Product-Name:~$ sudo cat /etc/mysql/debian.cnf
# Automatically generated for Debian scripts. DO NOT TOUCH!
[client]
host     = localhost
user     = debian-sys-maint
password = xxxxxxxx
socket   = /var/run/mysqld/mysqld.sock
[mysql_upgrade]
host     = localhost
user     = debian-sys-maint
password = xxxxxxxx
socket   = /var/run/mysqld/mysqld.sock

2.修改root密碼

用找到的使用者名稱和密碼登陸，我用的是dbeaver，建立新的連線，選擇MySQL。

方法1：

update mysql.user set authentication_string=password('123456') where user='root' and Host = 'localhost';

方法2：

ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';

方法3：

set password for root@localhost = password('123');

3.修改plugin欄位內容為mysql_native_password

update mysql.user set plugin='mysql_native_password'  where user='root' and Host = 'localhost';
flush privileges ; 

如果沒有修改plugin欄位為 mysql_native_password，用新密碼無法成功登陸。因為沒有更新這個欄位，被坑的好苦…