ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'mysql'

mysql> use mysql
ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'mysql'

解決辦法：

# mysqld_safe --skip-grant-table
161104 10:36:00 mysqld_safe Logging to '/var/log/mysqld.log'.
161104 10:36:00 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

此時該終端處於等待狀態，另外開啓一個終端修改mysql的root口令

# mysql -u root

mysql> update user set password=PASSWORD('') where user='root';    #這裏我設置root口令爲空
Query OK, 0 rows affected (0.00 sec)
Rows matched: 3  Changed: 0  Warnings: 0

mysql> delete from user where user='';             #刪除這個''@‘localhost’用戶，不然登陸後仍是默認這個用戶
Query OK, 2 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> quit

修改完mysql的root用戶口令之後，中止mysqld的服務，此時，上面的終端等待將中止。

# /etc/init.d/mysqld restop
Stopping mysqld:  [  OK  ]

Starting mysqld:  [  OK  ]

再次登陸mysql問題解決。