root用戶登陸數據庫登陸不進去，報以下錯誤，然后重新修改了密碼，具體操作如下：
配置文件中加了skip-grant-tables，用/etc/init.d/mysqld重啟之后可以進去了；所以一定是密碼的問題，所以我開始改密碼。
##我們把root@localhost用戶刪了，然后有新建了這個用戶
mysql> delete from mysql.user where user='root' and host='localhost';
Query OK, 1 row affected (0.01 sec)
mysql> select user,host from mysql.user;
+-----------+-----------+
| user | host |
+-----------+-----------+
| mysql.sys | localhost |
+-----------+-----------+
1 row in set (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> grant all on *.* to 'root'@'localhost' identified by '123456';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> select user,host from mysql.user;
+-----------+-----------+
| user | host |
+-----------+-----------+
| mysql.sys | localhost |
| root | localhost |
+-----------+-----------+
2 rows in set (0.01 sec)
但是到這還是不行，你用下面的命令會發現一個情況
mysql> select * from mysql.user\G;
Grant顯示N--mysql權限架構體系（應該是這么說）是關閉的，所以得執行以下操作：
mysql> grant all on *.* to 'root'@'localhost' identified by '123456' with grant option;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
退出mysql，將skip-grant-tables注掉，然后重啟mysql。此時在登陸就可以了。