MySQL user表被删除了怎么办

数据库干货铺 2020-04-25

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技术交流群总是能带来很多实际生产环境遇到的问题，例如，近期就有人遇到user表内容被清空的情况。如果发生了此情况，千万不要慌，更不能隐瞒问题（这位朋友就比较惨，别人删了也没敢告知，结果binlog已经清理了），以免不利于恢复。现在针对几种情况，进行恢复操作的演示。

user表被delete

如果有权限的同学误执行了情况mysql.user表内容的情况，如果是delete的方式还是相对容易恢复的（binlog存在的情况）

1.1 模拟误删除

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/* 当前user表的内容 */
mysql> select user,host from mysql.user;
+---------------+--------------+
| user          | host         |
+---------------+--------------+
| repl          | 192.168.28.% |
| mysql.session | localhost    |
| mysql.sys     | localhost    |
| root          | localhost    |
+---------------+--------------+
4 rows in set (0.00 sec)


mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2020-04-16 06:37:07 |
+---------------------+
1 row in set (0.00 sec)
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现在执行误删除

mysql> delete from  mysql.user;
Query OK, 4 rows affected (0.01 sec)


mysql>
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1.2 恢复

当前情况下，如开启了binlog（生产环境一般都是开启了的），则可以从binlog恢复

注意如果有全部及其之后的binlog 则可以通过恢复备份并追加binlog的方式恢复数据（后续其他文章再专题介绍），本文基于无全备，仅有最近的日志情况下恢复（主要是为了使用binlog2sql工具）

1.2.1 先恢复root账号

因为删除后，其他用户无法重新连接数据库了，需要紧急恢复root账号，再做后续其他账号的恢复，恢复步骤为：

修改为跳过授权的模式，即在配置文件my.cnf文件中添加 skip-grant-tables

重启数据库

登录数据库，添加root@'localhost'账号(可以从相同版本数据库中导出一个root账号的sql语句恢复

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/usr/local/mysql5.7/bin/mysqldump -uroot -p'123456'  
-t --socket=/data/mysql3307/tmp/mysql.sock mysql user 
--where " 1=1 and  user='root' and host='localhost'" >1.sql
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恢复数据

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> INSERT INTO `user` VALUES ('localhost','root','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0,'mysql_native_password',password('123456'),'N',now(),NULL,'N');
Query OK, 1 row affected (0.01 sec)
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改为授权模式：将配置文件里的 skip-grant-tables 注释或删除

再次重启数据库即可用刚恢复的root账号登录了

mysql> select user,host from mysql.user;
+------+-----------+
| user | host      |
+------+-----------+
| root | localhost |
+------+-----------+
1 row in set (0.00 sec)
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注：如果清空数据或后续说的删除了user表后没有退出当前会话，就无需之前的修改参数及重启数据库了，可以直接先从其他实例中先恢复root账号。

1.2.2 安装binlog2sql

binlog2sql依赖python2.7及以上版本，且依赖包通过pip安装，对于python的升级及pip的安装可参考历史文章

升级python，就是这么简单

一分钟搞定pip安装

yum install -y git wget
git clone https://github.com/danfengcao/binlog2sql.git && cd binlog2sql
pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple
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1.2.3 使用binlog2sql工具恢复数据

使用binlog2sql的闪回工具将删除解析处理生成一个insert的sql脚本

python binlog2sql.py --flashback  
-h localhost -u root -p 123456 -d mysql -t user 
--start-file='mysql-bin.000002' --start-datetime='2020-04-16 06:37:07' --stop-datetime='2020-04-16 06:40:00' >mysql.sql
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将数据导入mysql.user表即可。

注：关于binlog2log的其他用法请参考https://github.com/danfengcao/binlog2sql

user表被drop

2.1 模拟user 表被drop

mysql> drop table mysql.user;
Query OK, 0 rows affected (0.01 sec)
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2.2 恢复

2.2.1 恢复表结构

表结构的恢复比较简单，可以从其他相同版本的数据库里复制user表的建表语句，然后导入即可

CREATE TABLE `user` (
  `Host` char(60) COLLATE utf8_bin NOT NULL DEFAULT '',
  `User` char(32) COLLATE utf8_bin NOT NULL DEFAULT '',
  `Select_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Insert_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Update_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Delete_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Drop_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Reload_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Shutdown_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Process_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `File_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Grant_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `References_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Index_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Alter_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Show_db_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Super_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_tmp_table_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Lock_tables_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Execute_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Repl_slave_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Repl_client_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_view_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Show_view_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_routine_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Alter_routine_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_user_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Event_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Trigger_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `Create_tablespace_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `ssl_type` enum('','ANY','X509','SPECIFIED') CHARACTER SET utf8 NOT NULL DEFAULT '',
  `ssl_cipher` blob NOT NULL,
  `x509_issuer` blob NOT NULL,
  `x509_subject` blob NOT NULL,
  `max_questions` int(11) unsigned NOT NULL DEFAULT '0',
  `max_updates` int(11) unsigned NOT NULL DEFAULT '0',
  `max_connections` int(11) unsigned NOT NULL DEFAULT '0',
  `max_user_connections` int(11) unsigned NOT NULL DEFAULT '0',
  `plugin` char(64) COLLATE utf8_bin NOT NULL DEFAULT 'mysql_native_password',
  `authentication_string` text COLLATE utf8_bin,
  `password_expired` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  `password_last_changed` timestamp NULL DEFAULT NULL,
  `password_lifetime` smallint(5) unsigned DEFAULT NULL,
  `account_locked` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
  PRIMARY KEY (`Host`,`User`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='Users and global privileges'
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