1 故障现象：

在创建用户时候，提示以下错误：

root@localhost Tue Oct 24 09:57:41 2017 09:57:41 [mysql]> create user 'liufofu'@'5.5.5.5' identified by 'liufofu'; 

ERROR 1805 (HY000): Column count of mysql.user is wrong. Expected 45, found 43. The table is probably corrupted

2 原因分析

2.1 根据提示以为是数据表出问题了，赶紧查查看，但是数据表可以正常查询

root@localhost Tue Oct 24 09:54:15 2017 09:54:15 [(none)]> select count(*) from mysql.user where user='liufofu' and host='5.5.5.5';

+----------+

| count(*) |

+----------+

| 0 |

+----------+

1 row in set (0.01 sec)

2.2 对数据表进行一次check table操作

root@localhost Tue Oct 24 09:57:50 2017 09:57:50 [mysql]> check table user;

+------------+-------+----------+----------+

| Table | Op | Msg_type | Msg_text |

+------------+-------+----------+----------+

| mysql.user | check | status | OK |

+------------+-------+----------+----------+

1 row in set (0.00 sec)

2.3 进行了以上操作后，发现还是不行。

跟使用人员进行沟通后，得出结果是：用户在创建时选择的是MySQL5.7的版本，而导入的备份文件为MySQL5.6的，版本不一致导致MySQL系统表有差异所之后。

3 解决方案

知道问题后，处理方案就很容易了，升级系统表即可。

[ 09:59:27-root@liufofu:3311 ]#/usr/local/mysql-5.7.18/bin/mysql_upgrade -S /data/mysql/3311/mysql.sock

Checking if update is needed.

Checking server version.

Running queries to upgrade MySQL server.

Checking system database.

mysql.columns_priv OK

mysql.db OK

mysql.engine_cost OK

mysql.event OK

mysql.func OK

mysql.general_log OK

mysql.gtid_executed OK

mysql.help_category OK

mysql.help_keyword OK

mysql.help_relation OK

mysql.help_topic OK

mysql.innodb_index_stats OK

mysql.innodb_table_stats OK

mysql.ndb_binlog_index OK

mysql.plugin OK

mysql.proc OK

mysql.procs_priv OK

mysql.proxies_priv OK

mysql.server_cost OK

mysql.servers OK

mysql.slave_master_info OK

mysql.slave_relay_log_info OK

mysql.slave_worker_info OK

mysql.slow_log OK

mysql.tables_priv OK

mysql.time_zone OK

mysql.time_zone_leap_second OK

mysql.time_zone_name OK

mysql.time_zone_transition OK

mysql.time_zone_transition_type OK

mysql.user OK

The sys schema is already up to date (version 1.5.1).

Found 0 sys functions, but expected 22. Re-installing the sys schema.

Upgrading the sys schema.

Checking databases.

sys.sys_config OK

Upgrade process completed successfully.

Checking if update is needed.

到此用户的问题得到了解决。

4 参考资料：

4.1 mysql_upgrade官方文档

https://dev.mysql.com/doc/refman/5.7/en/mysql-upgrade.html

4.2 create user官方文档

MySQL5.7之前基本都是通过grant来创建用户，而从5.7开始建议使用create user来创建用户。

https://dev.mysql.com/doc/refman/5.7/en/create-user.html