我将尝试用几句话来解释这里发生了什么...
我已经在Ubuntu Server（18.04）版本上创建了一个MySQL 8数据库的干净实例。该数据库运行正常，我可以使用来自另一台服务器的SSH进行本地和远程连接。
作记录，
user@server:~$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 44
并且在连接时，我在mysql db上发出此命令SELECT HOST, USER FROM user并得到：
+---------------+------------------+
| HOST | USER |
+---------------+------------------+
| 192.168.0.xxx | phpMyAdmin |
| localhost | mysql.infoschema |
| localhost | mysql.session |
| localhost | mysql.sys |
| localhost | root |
+---------------+------------------+
到目前为止，很好。下一步，我创建一个特定的用户（例如，将其命名为Usr1）：CREATE USER Usr1@'192.168.0.xxx' IDENTIFIED WITH mysql_native_password BY 'foo'然后重复完全相同的命令三遍，只更改用户名和密码，而不更改其他任何内容。
当我尝试远程连接（使用在用户创建中已经指定的主机）时，usr3可以连接，而user1和user2无法连接；对于这些用户，我看到此错误：
[email protected]:~$ mysql -u User1 -h 192.168.0.yyy -p
ERROR 1045 (28000): Access denied for user 'User1'@'192.168.0.xxx' (using password: YES)
[email protected]:~$ mysql -u User2 -h 192.168.0.yyy -p
ERROR 1045 (28000): Access denied for user 'User2'@'192.168.0.xxx' (using password: YES)
而且我很确定我没有写错密码！使用“ User3”，我可以连接和查询数据库，没问题。使用“ User1”或“ User2”，我收到上面的消息错误。
然后，尽管为每个用户编写了相同的命令，但我查询mysql.user表，并比较结果中的每一列；正如预期的那样，除“用户”和“密码”外，所有列的值都完全相同。为了清楚起见，我在这里显示结果，但是正如我已经提到的，各列完全相同...
+---------------+----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| Host | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Reload_priv | Shutdown_priv | Process_priv | File_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Show_db_priv | Super_priv | Create_tmp_table_priv | Lock_tables_priv | Execute_priv | Repl_slave_priv | Repl_client_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Create_user_priv | Event_priv | Trigger_priv | Create_tablespace_priv | ssl_type | ssl_cipher | x509_issuer | x509_subject | max_questions | max_updates | max_connections | max_user_connections | plugin | authentication_string | password_expired | password_last_changed | password_lifetime | account_locked | Create_role_priv | Drop_role_priv | Password_reuse_history | Password_reuse_time | Password_require_current | User_attributes |
+---------------+----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| 192.168.0.xxx | User1 | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | * | N | 2020-04-10 19:43:13 | NULL | N | N | N | NULL | NULL | NULL | NULL |
| 192.168.0.xxx | User2 | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | * | N | 2020-04-10 19:42:54 | NULL | N | N | N | NULL | NULL | NULL | NULL |
| 192.168.0.xxx | User3 | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | * | N | 2020-04-10 18:34:12 | NULL | N | N | N | NULL | NULL | NULL | NULL |
+---------------+----------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
从这一点上说出了主意。有什么想法吗？
提前感谢！
我终于设法了解了（或有些类似于理解...）问题所在。无论为每个用户发出完全相同的命令，我创建的第一个命令都可以直接访问安装MySQL的服务器。另外两个用户是在另一台服务器上创建的，其中一台服务器安装了phpMyAdmin和Apache。
[出于任何未知（至少对我而言）原因，我使用“ root” @“ IP”创建的用户无法连接到MySQL安装，而我使用“ root” @“ localhost创建的用户”的连接很好。我使用“ root” @“ localhost”帐户删除并重新创建了用户，尽管mysql.user表上的信息仍然相同，但他们仍能够连接到数据库。
无论如何，现在我可以使用所有三个帐户进行连接，每个帐户都可以从一开始就访问特定的数据库。