密码和用户名都是正确的，但登录后报如下错误：
ERROR 1045 (28000): Access denied for user ‘admin’@'localhost’ (using password: YES)
尝试了加入-h和-port也无法登陆，最后只能重新修改了。 注--该方法也可以用于当忘记数据库密码时，找回数据库密码用
如下是我执行过程，完全执行后，可以顺利登录数据库：linux下的执行脚本：
login as: root
Access denied
root@×××××××'s password:
Last login: Tue Feb 21 03:56:49 2012 from 218.17.162.225
[root@INOTRADE ~]# ps -A
PID TTY TIME CMD
1 ? 00:00:01 init
1117 ? 00:00:00 udevd
1394 ? 00:00:00 syslogd
1405 ? 00:00:00 sshd
1414 ? 00:00:00 xinetd
1427 ? 00:00:00 couriertcpd
1429 ? 00:00:00 courierlogger
1437 ? 00:00:00 couriertcpd
1439 ? 00:00:00 courierlogger
1445 ? 00:00:00 couriertcpd
1447 ? 00:00:00 courierlogger
1454 ? 00:00:00 couriertcpd
1456 ? 00:00:00 courierlogger
1466 ? 00:00:00 qmail-send
1468 ? 00:00:00 splogger
1469 ? 00:00:00 qmail-lspawn
1470 ? 00:00:00 qmail-rspawn
1471 ? 00:00:00 qmail-clean
1486 ? 00:00:00 httpd
1528 ? 00:00:00 named
1573 ? 00:00:00 mysqld_safe
1623 ? 00:00:00 mysqld
1629 ? 00:00:00 httpd
1655 ? 00:00:00 httpsd
1659 ? 00:00:00 httpsd
1674 ? 00:00:00 crond
1682 ? 00:00:00 saslauthd
1683 ? 00:00:00 saslauthd
1689 ? 00:00:00 sshd
1691 pts/0 00:00:00 bash
1718 pts/0 00:00:00 ps
// 无法登陆，密码正确的，不知道为什么，原来数据库表的访问权限也已经设置了的
[root@INOTRADE ~]# mysql -uroot -p
Enter password:
[root@INOTRADE ~]# ERROR 1045 (28000): Access denied for user ‘admin’@'localhost’ (using password: YES)
[root@INOTRADE ~]# mysql -uroot -p****** -hlocalhost
[root@INOTRADE ~]# ERROR 1045 (28000): Access denied for user ‘admin’@'localhost’ (using password: YES)
// 执行脚本，更新mysql数据库的数据，如用户名密码
[root@INOTRADE ~]# sudo /etc/init.d/mysqld stop
Stopping MySQL: [ OK ]
[root@INOTRADE ~]# mysqld_safe --user=mysql --skip-grant-tables --skip-networking &
[1] 1759
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@INOTRADE ~]# Starting mysqld daemon with databases from /var/lib/mysql
-- 这步可能不会自动执行，等待十几秒后就可以直接回车返回到命令行模式下，然后登录到mysql服务器
[root@INOTRADE ~]#
[root@INOTRADE ~]# mysql -u root mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.77 Source distribution
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> select host, user from user;
+-----------+------------------+
| host | user |
+-----------+------------------+
| % | admin |
| localhost | admin |
| localhost | horde |
| localhost | pma_OBBVuV2L3mjn |
+-----------+------------------+
4 rows in set (0.00 sec)
-- 因为我数据库中没有root，换为admin了
mysql> UPDATE user SET Password=PASSWORD('******') where USER='admin';
Query OK, 2 rows affected (0.02 sec)
Rows matched: 2 Changed: 2 Warnings: 0
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.02 sec)
mysql> quit;
Bye
[root@INOTRADE ~]# /etc/init.d/mysqld restart
STOPPING server from pid file /var/run/mysqld/mysqld.pid
120221 05:08:02 mysqld ended
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]
[1]+ Done mysqld_safe --user=mysql --skip-grant-tables --skip-networking
// 至此， 重启后就可以正常登录了
[root@INOTRADE ~]# mysql -uadmin -p******
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.0.77 Source distribution
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> show databases;
+-------------------------+
| Database |
+-------------------------+
| information_schema |
| ******* |
| horde |
| mysql |
+-------------------------+
7 rows in set (0.01 sec)
mysql> use ********;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+------------------------------+
| Tables_in_CQT_AMS |
+------------------------------+
| T_ALM_APPLICATION |
| ***************** |
| T_SYS_ROLE |
| T_SYS_USER_INFO |
| T_SYS_USER_ROLE |
+------------------------------+
22 rows in set (0.00 sec)
mysql> quit
Bye
[root@INOTRADE ~]#
以上代码，参考了网上的相关资料