筆者曾經有一次誤刪了mysqlroot用戶，怎麽辦？

之前的解決方式是通過忽略授權表的方式重啟mysql然後插入相關數據解決該問題的，但是這種方式需要重啟mysql，會影響現有業務，那麽有沒有其他方式可以不重啟MySQL就解決呢?

因為mysql的user表示MyISAM引擎的，因此我們可以通過修改對應的文件來解決這個問題。下面是本人在測試環境的一次演練，僅供參考。

一、查看現有用戶

04:18:34 root@localhost [mysql]>select user,host from user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
+---------------+-----------+
3 rows in set (0,00 sec)
 

二、刪除本地root用戶

04:18:59 root@localhost [mysql]>drop user root@‘localhost‘;

三、再次查看用戶

04:20:02 root@localhost [mysql]>select user,host from user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| mysql.session | localhost |
| mysql.sys     | localhost |
+---------------+-----------+
 

現在我們開始恢復用戶數據

四、移動user表相關文件

[root@localhost mysql]# cp user.* /vagrant/mysql/3307/data/test/

五、登錄另一個實例並查看user表

04:23:53 root@localhost [(none)]>use test;
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
04:23:56 root@localhost [test]>show tables;
+----------------+
| Tables_in_test |
+----------------+
| user           |
+----------------+
1 row in set (0,00 sec)

04:23:58 root@localhost [test]>select * from user\G
*************************** 1. row ***************************
                  Host: localhost
                  User: mysql.session
           Select_priv: N
           Insert_priv: N
           Update_priv: N
           Delete_priv: N
           Create_priv: N
             Drop_priv: N
           Reload_priv: N
         Shutdown_priv: N
          Process_priv: N
             File_priv: N
            Grant_priv: N
       References_priv: N
            Index_priv: N
            Alter_priv: N
          Show_db_priv: N
            Super_priv: Y
 Create_tmp_table_priv: N
      Lock_tables_priv: N
          Execute_priv: N
       Repl_slave_priv: N
      Repl_client_priv: N
      Create_view_priv: N
        Show_view_priv: N
   Create_routine_priv: N
    Alter_routine_priv: N
      Create_user_priv: N
            Event_priv: N
          Trigger_priv: N
Create_tablespace_priv: N
              ssl_type:
            ssl_cipher:
           x509_issuer:
          x509_subject:
         max_questions: 0
           max_updates: 0
       max_connections: 0
  max_user_connections: 0
                plugin: mysql_native_password
 authentication_string: *C7A1AAE2D250AFD864050FAF4935EF6F5D185A92
      password_expired: N
 password_last_changed: 2018-02-23 13:19:12
     password_lifetime: NULL
        account_locked: Y
*************************** 2. row ***************************
                  Host: localhost
                  User: mysql.sys
           Select_priv: N
           Insert_priv: N
           Update_priv: N
           Delete_priv: N
           Create_priv: N
             Drop_priv: N
           Reload_priv: N
         Shutdown_priv: N
          Process_priv: N
             File_priv: N
            Grant_priv: N
       References_priv: N
            Index_priv: N
            Alter_priv: N
          Show_db_priv: N
            Super_priv: N
 Create_tmp_table_priv: N
      Lock_tables_priv: N
          Execute_priv: N
       Repl_slave_priv: N
      Repl_client_priv: N
      Create_view_priv: N
        Show_view_priv: N
   Create_routine_priv: N
    Alter_routine_priv: N
      Create_user_priv: N
            Event_priv: N
          Trigger_priv: N
Create_tablespace_priv: N
              ssl_type:
            ssl_cipher:
           x509_issuer:
          x509_subject:
         max_questions: 0
           max_updates: 0
       max_connections: 0
  max_user_connections: 0
                plugin: mysql_native_password
 authentication_string: *C7A1AAE2D250AFD864050FAF4935EF6F5D185A92
      password_expired: N
 password_last_changed: 2018-02-23 13:19:26
     password_lifetime: NULL
        account_locked: Y
2 rows in set (0,00 sec)
 

六、把本實例的root用戶插入剛剛移動過來的user表

04:25:03 root@localhost [test]>insert into user select * from mysql.user where user = ‘root‘ and host =‘localhost‘;
Query OK, 1 row affected (0,02 sec)
Records: 1  Duplicates: 0  Warnings: 0

七、再次移動user文件到原先的位置

[root@localhost test]# cp user.* /vagrant/mysql/3306/data/mysql

八、重新加載配置到內存

[root@localhost test]# kill -HUP `pidof mysqld`

通過該步mysql並不會重啟，對應用不會有影響

九、重新登錄，OK

[root@localhost test]# mysql -uroot -p -S /tmp/mysql3306.sock
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 13
Server version: 5.7.21-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.

04:30:57 root@localhost [(none)]>

【MySQL】mysql root密碼忘記怎麽辦？