看这个账户有点碍眼就删除了，结果异常了
mysql> select user,host from mysql.user;
+---------------+-------------+
| user | host |
+---------------+-------------+
| repmha | 192.168.5.% |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+---------------+-------------+
4 rows in set (0.00 sec)
mysql> drop user root@‘localhost‘;
Query OK, 0 rows affected (0.01 sec)
登录异常：库中已没了root用户
[root@test110 ~]# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user ‘root‘@‘localhost‘ (using password: YES)
修改异常：现在本身就没root用户所以没法修改，无论哪种方式修改，都要先有
mysql> set password for ‘root‘@‘localhost‘ = password(‘123456‘);
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql> ALTER USER ‘root‘@‘localhost‘ IDENTIFIED BY ‘123456‘;
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql> ALTER USER ‘root‘@‘localhost‘ IDENTIFIED WITH mysql_native_password BY ‘123456‘;
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
1、修改my.cnf
vi /etc/my.cnf
--添加
skip-grant-tables
2、重启
service mysqld restart
3、登录
[root@xxxx ~]# mysql -uroot -p123456
mysql> use mysql;
Database changed
mysql> select user , host from user;
+---------------+-------------+
| user | host |
+---------------+-------------+
| monitor | 192.168.5.% |
| repmha | 192.168.5.% |
| mysql.session | localhost |
| mysql.sys | localhost |
+---------------+-------------+
4 rows in set (0.00 sec)
4、重新添加，有时候会出现错误，可以先flush下
mysql> grant all on *.* to root@‘localhost‘ identified by ‘123456‘;
Query OK, 0 rows affected, 2 warnings (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
5、root又回来了
mysql> select user , host from user;
+---------------+-------------+
| user | host |
+---------------+-------------+
| monitor | 192.168.5.% |
| repmha | 192.168.5.% |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+---------------+-------------+
5 rows in set (0.00 sec)
6、删除 /etc/my.cnf中 skip-grant-tables ，再重启 service mysqld restart
没事别瞎胡整，删除动作很危险。
原文：https://www.cnblogs.com/ritchy/p/11940485.html