ubuntu25.10安裝mysql，設置root密碼

sudo apt update
sudo apt install mysql-server
sudo mysql

[sudo: authenticate] Password: 
....
Your MySQL connection id is 8
Server version: 8.4.6-0ubuntu3 (Ubuntu)
.....

二、mysql_secure_installation 一樣使用sudo;

sudo mysql_secure_installation

 　　　　按提示進行安全設置。

三、默認情況下，mysql使用auth_socket進入root用戶認證（這是root用戶無法用密碼進入的原因）,
MySQL服務器也啟用了 caching_sha2_password 插件；

mysql> use mysql
mysql> select user,authentication_string,plugin from user;

　　　　 +------------------+------------------------------------------------------------------------+-----------------------+

| user             | authentication_string                                                  | plugin                |
+------------------+------------------------------------------------------------------------+-----------------------+
| debian-sys-maint | root                                                                   | auth_socket           |
| mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| root             |                                                                        | auth_socket           |
+------------------+------------------------------------------------------------------------+-----------------------+
5 rows in set (0.00 sec)
四、我們需將root認證方式改為caching_sha2_password方式，并用此方式設置root密碼；

mysql> update user set plugin='caching_sha2_password' where user='root';
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH caching_sha2_password BY 'your_password';
mysql> select user,authentication_string,plugin from user;

+------------------+------------------------------------------------------------------------+-----------------------+
| user             | authentication_string                                                  | plugin                |
+------------------+------------------------------------------------------------------------+-----------------------+
| debian-sys-maint | root                                                                   | auth_socket           |
| mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| root             | $A$005$?HAqF#gtm}+
                                       	d,0ST46h11SEo0IioxCHTmZ.9cjqRml6aD1jM6FRC7uCA | caching_sha2_password |
+------------------+------------------------------------------------------------------------+-----------------------+
5 rows in set (0.00 sec)
五、成功

mysql> exit;
~$ mysql -uroot -p

 Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 11
Server version: 8.4.6-0ubuntu3 (Ubuntu)
...
完成。