背景：
将mysql 5.6.31版本的数据导入mysql 5.6.45后出现mysql.user表坏掉的情况
出现问题：mysql.user表坏了
root@192.168.1.2 ((none)) > grant all privileges on . to root@'%' identified by "M22221";
ERROR 1805 (HY000): Column count of mysql.user is wrong. Expected 43, found 44. The table is probably corrupted
Mon Dec 13 17:31:40 2021
解决办法：1.升级mysql一下：mysql_upgrade
[work@192.168.1.2]$ mysql_upgrade -udba -pdba -h192.168.1.2 -P3307
mysql_upgrade: [Warning] Using a password on the command line interface can be insecure.
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
Checking system database.
mysql.columns_priv OK
mysql.db OK
2.alter user 表
mysql -u root -p
use mysql;
alter table mysql.user drop column default_role;
alter table mysql.user drop column max_statement_time;
alter table mysql.user drop column password_expired;
quit
