mysql“Access denied for user 'root'@'localhost'”问题的解决

我的Ubuntu系统最近使用mysql工具时，出现错误提示:

li@ubuntu:~$ mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

直接使用/etc/mysql/debian.cnf文件中[client]节提供的用户名和密码:
# mysql -u debian-sys-maint -p
Enter password: <输入[client]节的密码>

//mysql>登陆成功后修改user表

mysql>UPDATE user SET password='newpassword' WHERE user='root';

OK，已解决！重新登陆试一下：

#mysql -u root -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.1.49-1ubuntu8.1 (Ubuntu)


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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user,host,password fromuser;
ERROR 1046 (3D000): No database selected
mysql> select user,host,password from mysql.user;
+------+-----------+----------+
| user | host      | password |
+------+-----------+----------+
| root | localhost | li       |
| li   | localhost | li       |
+------+-----------+----------+
2 rows in set (0.00 sec)