因为重装了系统，而在重装Mysql过程中出现意想不到的错误，导致安装完成后出现：“mysql“Access denied for user 'root'@'localhost' ”。

折腾几个小时，终于搞定。

到WINDOWS的命令行了（‘DOS’ 下），切换到MySQL bin目录下。 比如我的是 D:\Program Files\MySQL\MySQL Server 5.1\bin
然后敲下面的粗体的命令。注意my.ini位置。

D:\Program Files\MySQL\MySQL Server 5.1\bin>mysqld --defaults-file="D:\Program
Files\MySQL\MySQL Server 5.1\my.ini" --console --skip-grant-tables
090515 22:06:09 [Warning] The syntax '--log' is deprecated and will be removed i
n MySQL 7.0. Please use '--general_log'/'--general_log_file' instead.
090515 22:06:09 [Warning] The syntax '--log_slow_queries' is deprecated and will
be removed in MySQL 7.0. Please use '--slow_query_log'/'--slow_query_log_file'
instead.
090515 22:06:09 [Warning] The syntax '--log' is deprecated and will be removed i
n MySQL 7.0. Please use '--general_log'/'--general_log_file' instead.
090515 22:06:09 [Warning] The syntax '--log_slow_queries' is deprecated and will
be removed in MySQL 7.0. Please use '--slow_query_log'/'--slow_query_log_file'
instead.
090515 22:06:09 [ERROR] The update log is no longer supported by MySQL in versio
n 5.0 and above. It is replaced by the binary log. Now starting MySQL with --log
-bin='' instead.
090515 22:06:09 InnoDB: Started; log sequence number 0 324221
090515 22:06:09 [Note] mysqld: ready for connections.
Version: '5.1.33-community-log' socket: '' port: 3306 MySQL Community Server
(GPL)

看到这个结果就说明MySQL已经起来了。
再开一个DOS窗口，同样切到mysql bin目录下，
D:\Program Files\MySQL\MySQL Server 5.1\bin>mysql -uroot mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.1.33-community-log MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>


然后

# /etc/init.d/mysql stop
# mysqld_safe --user=mysql --skip-grant-tables --skip-networking &
# mysql -u root mysql
mysql> UPDATE user SET Password=PASSWORD(’newpassword’) where USER=’root’;
mysql> FLUSH PRIVILEGES;
mysql> quit
# /etc/init.d/mysql restart
# mysql -uroot -p
Enter password: <输入新设的密码newpassword>
mysql>