如果您在 MySql 5.7. 中遇到相同的問題：

Access denied for user 'root'@'localhost'

這是因為MySql 5.7預設允許使用socket連接，這意味著你只需使用sudo mysql連接即可。如果你執行sql：

SELECT user,authentication_string,plugin,host FROM mysql.user;

然後你就會看到它：

+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             |                                           | auth_socket           | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *497C3D7B50479A812B89CD12EC3EDA6C0CB686F0 | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+
4 rows in set (0.00 sec)

要允許使用 root 和密碼進行連接，請使用命令更新表中的值：

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'Current-Root-Password';
FLUSH PRIVILEGES;

然後再次執行 select 命令，您將看到它已更改：

+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             | *2F2377C1BC54BE827DC8A4EE051CBD57490FB8C6 | mysql_native_password | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *497C3D7B50479A812B89CD12EC3EDA6C0CB686F0 | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+
4 rows in set (0.00 sec)

就是這樣。您可以在執行並完成 sudo mysql_secure_installation 指令後執行此程序。

對於 mariadb，請使用

SET PASSWORD FOR 'root'@'localhost' = PASSWORD('manager');