MySQL8.0及以上版本如何修改root密碼

1.如果記得原密碼，以原密碼登錄MySQL。否則需要先修改my.cnf文件，在mysqld模塊中增加一行：skip-grant-tables，然後重啓mysqld，並以空密碼登錄（直接回車）。

$ mysql -uroot -p
Enter password:

2.修改密碼。

mysql> alter user root@'%' identified by [with mysql_native_password] 'Admin123!@#';
Query OK, 0 rows affected (0.02 sec)】

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

注意，這裏可能需要一個高強度的密碼，MySQL8默認的驗證密碼強度（validate_password_policy）爲"MEDIUM"，可通過下面語句查詢當前密碼強度：

mysql> show variables like "%validate_password%";
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password_check_user_name    | ON     |
| validate_password_dictionary_file    |        |
| validate_password_length             | 8      |
| validate_password_mixed_case_count   | 1      |
| validate_password_number_count       | 1      |
| validate_password_policy             | MEDIUM |
| validate_password_special_char_count | 1      |
+--------------------------------------+--------+
7 rows in set (0.11 sec)

// 如果要修改密碼強度，可以執行下面語句
mysql> set global validate_password_policy=LOW;
Query OK, 0 rows affected (0.03 sec)

若以上不起作用，則可以先刪除root用戶，再新增root用戶。

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> delete from user where user='root';
Query OK, 1 row affected (0.02 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql> create user 'root'@'%' identified by 'Admin123!@#';
Query OK, 0 rows affected (0.01 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> grant all privileges on *.* to root@'%';
Query OK, 0 rows affected (0.01 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

然後重啓mysqld，用root用戶的新密碼登錄即可。