连接MySQL出现错误：ERROR 1045 (28000): Access denied for user ‘root‘@‘localhost‘ (using password: YES)

1、错误代码

[root@iZuf6el9zfn76jfyw0aoi9Z /]# mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

• 一般这个错误是由密码错误引起的，解决的办法自然就是重置密码！
• 如果当前不是root用户，使用命令sudo su root切换至root用户，然后操作！

2、解决方法

• 执行如下命令查看MySQL数据库实例在启动时，会在哪些位置查找配置文件

  [root@iZuf6el9zfn76jfyw0aoi9Z /]# mysql --help | grep my.cnf
  order of preference, my.cnf, $MYSQL_TCP_PORT,
  /etc/mysql/my.cnf /etc/my.cnf ~/.my.cnf 
  

• 如上可知，是按照这个顺序去查找的配置文件
  /etc/mysql/my.cnf -> /etc/my.cnf -> ~/.my.cnf
• 并且MySQL数据库会以读取到的最后一个配置文件中的参数为准
• 在Linux环境下，配置文件一般放在/etc/my.cnf，并且是以.cnf为后缀；
• 在Windows环境下，配置文件一般在/mysql/my.ini，后缀名可能是.cnf，也可能是.ini

2.1、重置密码

• 重置密码就要跳过密码校验（按照上述查找配置文件的顺序，编辑最后一个文件）

  [root@iZuf6el9zfn76jfyw0aoi9Z etc]# vim my.cnf
  	
  [mysqld]
  port            = 3306
  socket          = /tmp/mysql.sock
  datadir = /www/server/data
  default_storage_engine = InnoDB
  performance_schema_max_table_instances = 400
  table_definition_cache = 400
  skip-external-locking
  key_buffer_size = 32M
  max_allowed_packet = 100G
  table_open_cache = 128
  sort_buffer_size = 768K
  net_buffer_length = 4K
  read_buffer_size = 768K
  read_rnd_buffer_size = 256K
  myisam_sort_buffer_size = 8M
  thread_cache_size = 16
  query_cache_size = 16M
  tmp_table_size = 32M
  sql-mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
  
  explicit_defaults_for_timestamp = true
  #skip-name-resolve
  max_connections = 500
  max_connect_errors = 100
  open_files_limit = 65535
  

• 定位到[mysqld]，在其下方添加skip-grant-tables跳过密码校验

  [mysqld]
  skip-grant-tables
  

• :wq保存my.cnf文档，并退出

2.2、重新启动MySQL

• 输入如下命令

  /etc/init.d/mysql restart
  #有的可能是需要是mysqld
  /etc/init.d/mysqld restart
  

• 执行之后

  [root@iZuf6el9zfn76jfyw0aoi9Z mysql]# /etc/init.d/mysqld restart
  Shutting down MySQL..                                      [  OK  ]
  Starting MySQL.                                            [  OK  ]
  [root@iZuf6el9zfn76jfyw0aoi9Z mysql]# 
  

2.3、进入mysql中

• 在mysql安装目录下，直接进入mysql

  [root@iZuf6el9zfn76jfyw0aoi9Z mysql]# mysql
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  Your MySQL connection id is 1
  Server version: 5.6.50-log Source distribution
  
  Copyright (c) 2000, 2020, 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> 
  

• 首先选中mysql数据库

  mysql> show databases;
  +--------------------+
  | Database           |
  +--------------------+
  | information_schema |
  | mysql              |
  | performance_schema |
  +--------------------+
  4 rows in set (0.00 sec)
  
  mysql> use mysql
  Database changed
  mysql> 
  

• 执行sql修改密码

  mysql> update user set password=password("你的密码") where user="root";
  Query OK, 0 rows affected (0.00 sec)
  Rows matched: 4  Changed: 0  Warnings: 0
  

• 修改host匹配，允许所有客户端ip地址访问链接数据库

  mysql> update user set host = '%' where user = 'root' and host = '*';
  	Query OK, 0 rows affected (0.00 sec)
  	Rows matched: 0  Changed: 0  Warnings: 0
  	
  	mysql> select user,host from user where user = 'root';
  	+------+-------------------------+
  	| user | host                    |
  	+------+-------------------------+
  	| root | %                       |
  	| root | 127.0.0.1               |
  	| root | ::1                     |
  	| root | izuf6el9zfn76jfyw0aoi9z |
  	| root | localhost               |
  	+------+-------------------------+
  	5 rows in set (0.00 sec)
  

• 如果在修改上述host权限时，爆出如下错误

  #这说明已经修改为了%，无需再修改，直接进行下一步即可
  ERROR 1062 (23000): Duplicate entry '%-root' for key 'PRIMARY' 
  

• 修改成功后，刷新，退出（如果在执行该步骤的时候，出现其他错误，再次执行flush privileges;刷新即可）

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

• 到这里root账户就已经重置成新的密码了

2.4、重新编辑my.cnf去除刚才的跳过密码校验段

• 如果找不到my.cnf，在Linux环境下有快捷命令

  [root@iZuf6el9zfn76jfyw0aoi9Z etc]# whereis my
  my: /etc/my.cnf
  

• 即可定位到my.cnf在/etc目录下，然后重新vim编辑去除skip-grant-tables

• 再次重新启动MySQL

  /etc/init.d/mysql restart
  #有的可能是需要是mysqld	
  /etc/init.d/mysqld restart	
  

• 再次链接数据库

  [root@iZuf6el9zfn76jfyw0aoi9Z mysql]# mysql -uroot -p
  Enter password: #此处输入你的密码
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  Your MySQL connection id is 1
  Server version: 5.6.50-log Source distribution
  
  Copyright (c) 2000, 2020, 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> show databases;
  +--------------------+
  | Database           |
  +--------------------+
  | information_schema |
  | mysql              |
  | performance_schema |
  +--------------------+
  4 rows in set (0.00 sec)
  

• 妥了，大功告成！！！