linux版本：CentOS release 5.6
64位操作系统
mysql数据库：5.5.18
输入mysql -u root -p，然后输入密码，回车后报错如下：
linux ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
解决方法（转载）
原文网址：http://www.cnblogs.com/kerrycode/p/3861719.html
[root@DB-Server tmp]# rpm -ivh MySQL-server-5.6.19-1.rhel5.x86_64.rpm Preparing... ########################################### [100%] 1:MySQL-server ########################################### [100%] [root@DB-Server tmp]# rmp -ivh MySQL-client-5.6.19-1.rhel5.x86_64.rpm -bash: rmp: command not found [root@DB-Server tmp]# rpm -ivh MySQL-client-5.6.19-1.rhel5.x86_64.rpm Preparing... ########################################### [100%] 1:MySQL-client ########################################### [100%] [root@DB-Server tmp]# /etc/rc.d/init.d/mysql status MySQL is not running[FAILED] [root@DB-Server tmp]# /etc/rc.d/init.d/mysql start Starting MySQL.[ OK ] [root@DB-Server tmp]# mysql -u root -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) [root@DB-Server tmp]# mysql -u root mysql ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
解决方法：
首先停掉mysql服务器
[root@DB-Server init.d]# /etc/rc.d/init.d/mysql stop Shutting down MySQL..[ OK ]然后使用mysqld_safe命令在启动mysql，更新root账号的密码
--skip-grant-tables：不启动grant-tables(授权表),跳过权限控制。
--skip-networking ：跳过TCP/IP协议，只在本机访问(从网上有些资料看，这个选项不是必须的。可以不用)
[root@DB-Server init.d]# mysqld_safe --user=mysql --skip-grant-tables --skip-networking & [2] 9396 [root@DB-Server init.d]# 140722 14:59:46 mysqld_safe Logging to '/var/lib/mysql/DB-Server.err'. 140722 14:59:46 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
执行上面命令后，此会话窗口会出现无反应的状态，需要使用CTRL+C中断会话，检查/var/lib/mysql/DB-Server.err日志，发现也无其它异常信息。没有弄明白该会话窗口为啥会出现无响应状态。
ctrl+c 后如下结果：
tail -200 /var/lib/mysql/DB-Server.err | more 2014-07-22 14:59:41 9346 [Note] Shutting down plugin 'binlog' 2014-07-22 14:59:41 9346 [Note] /usr/sbin/mysqld: Shutdown complete 140722 14:59:41 mysqld_safe mysqld from pid file /var/lib/mysql/DB-Server.pid ended 140722 14:59:46 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 2014-07-22 14:59:47 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timesta mp server option (see documentation for more details). 2014-07-22 14:59:47 9516 [Note] Plugin 'FEDERATED' is disabled. 2014-07-22 14:59:47 9516 [Note] InnoDB: Using atomics to ref count buffer pool pages 2014-07-22 14:59:47 9516 [Note] InnoDB: The InnoDB memory heap is disabled 2014-07-22 14:59:47 9516 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins 2014-07-22 14:59:47 9516 [Note] InnoDB: Compressed tables use zlib 1.2.3 2014-07-22 14:59:47 9516 [Note] InnoDB: Using Linux native AIO 2014-07-22 14:59:47 9516 [Note] InnoDB: Using CPU crc32 instructions 2014-07-22 14:59:47 9516 [Note] InnoDB: Initializing buffer pool, size = 128.0M 2014-07-22 14:59:47 9516 [Note] InnoDB: Completed initialization of buffer pool 2014-07-22 14:59:47 9516 [Note] InnoDB: Highest supported file format is Barracuda. 2014-07-22 14:59:47 9516 [Note] InnoDB: 128 rollback segment(s) are active. 2014-07-22 14:59:47 9516 [Note] InnoDB: Waiting for purge to start 2014-07-22 14:59:47 9516 [Note] InnoDB: 5.6.19 started; log sequence number 1626087 2014-07-22 14:59:47 9516 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.6.19' socket: '/var/lib/mysql/mysql.sock' port: 0 MySQL Community Server (GPL)
然后输入如下命令
[root@DB-Server init.d]# 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: 5.6.19 MySQL Community Server (GPL)
Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select Host, User, Password,password_expired
-> from user
-> where user='root' and host='root' or host='localhost';
+-----------+------+-------------------------------------------+------------------+
| Host | User | Password | password_expired |
+-----------+------+-------------------------------------------+------------------+
| localhost | root | *A848DE7CCD839E924921BEE41711991DDA0D529E | Y |
+-----------+------+-------------------------------------------+------------------+
1 row in set (0.00 sec)
mysql> update user set password=PASSWORD('root')
-> where user='root' and host='root' or host='localhost';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
我在select用户表的时候结果为0 row ，也就是没有数据结果，需要用insert进行添加
insert into user set user='root’,ssl_cipher='',x509_issuer='',x509_subject='';
然后将其他字段添加上：
update user set Host=‘localhost’,select_priv=‘y', insert_priv=‘y',update_priv=‘y', Alter_priv=‘y’,delete_priv=‘y',create_priv=‘y',drop_priv=‘y',reload_priv=‘y',shutdown_priv=‘y',Process_priv=‘y',file_priv=‘y',grant_priv=‘y',References_priv=‘y',index_priv=‘y',create_user_priv=‘y',show_db_priv=‘y',super_priv=‘y',create_tmp_table_priv=‘y',Lock_tables_priv=‘y',execute_priv=‘y',repl_slave_priv=‘y',repl_client_priv=‘y',create_view_priv=‘y',show_view_priv=‘y',create_routine_priv=‘y',alter_routine_priv=‘y',create_user_priv=‘y’ where user=‘root’;
新设置用户或更改密码后需用flush privileges刷新MySQL的系统权限相关表，否则会出现拒绝访问，还有一种方法，就是重新启动mysql服务器，来使新设置生效。
mysql> flush privileges; Query OK, 0 rows affected (0.00 sec) mysql> quit Bye [root@DB-Server init.d]# /etc/rc.d/init.d/mysql restart Shutting down MySQL..140722 15:02:27 mysqld_safe mysqld from pid file /var/lib/mysql/DB-Server.pid ended [ OK ] Starting MySQL.[ OK ] [2]- Done mysqld_safe --user=mysql --skip-grant-tables --skip-networking [root@DB-Server init.d]# mysql -u root p ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) [root@DB-Server init.d]# mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.6.19 Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>至此问题解决
另外，如果登录mysql数据库后执行脚本遭遇 ERROR 1820 (HY000): You must SET PASSWORD before executing this statement,可以使用重新设置一次密码即可解决问题.
mysql>set password = password('root');