数据库之MySQL ERROR 1698 (28000) 错误：Access denied for user 'root'@'localhost'" error【摘抄】

声明：全文均摘抄于MySQL ERROR 1698 (28000) 错误

    //错误起源：
        ~$ mysql -u root -p
             Enter password: 
             ERROR 1698 (28000): Access denied for user 'root'@'localhost'

解决步骤：

1. 停止mysql服务

    ~$ sudo service mysql stop

2. 以安全模式启动MySQL

    ~$ sudo mysqld_safe --skip-grant-tables &

3. MySQL启动之后就可以不用密码登陆了

    ~$ mysql -u root
    Welcome to the MySQL monitor.  Commands end with ; or g.
    Your MySQL connection id is 2
    Server version: 5.7.10 MySQL Community Server (GPL)

4. 查看一下user表，错误的起因就是在这里， root的plugin被修改成了auth_socket，用密码登陆的plugin应该是mysql_native_password。

    mysql> select user, plugin from mysql.user;
    +-----------+-----------------------+
    | user      | plugin                |
    +-----------+-----------------------+
    | root      | auth_socket           |
    | mysql.sys | mysql_native_password |
    | dev       | mysql_native_password |
    +-----------+-----------------------+
    3 rows in set (0.01 sec)

5. 关于auth_socket，在官方有说明： https://dev.mysql.com/doc/mysql-security-excerpt/5.5/en/socket-authentication-plugin.html ，反正现在暂时不用它， 那就把这里改了。

    mysql> update mysql.user set authentication_string=PASSWORD('newPwd'), plugin='mysql_native_password' where user='root';#最关键一步骤
    Query OK, 1 row affected, 1 warning (0.00 sec)
    Rows matched: 1  Changed: 1  Warnings: 1

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

6. 重启服务，问题就解决了

    ~$ sudo service mysql stop
    ...
     * MySQL Community Server 5.7.10 is stopped
    ~$ sudo service mysql start
    ..
     * MySQL Community Server 5.7.10 is started
    ~$ mysql -u root -p
    Enter password: 
    Welcome to the MySQL monitor.  Commands end with ; or g.
    Your MySQL connection id is 2
    Server version: 5.7.10 MySQL Community Server (GPL)

7.linux云主机端：开启远程连接

    sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf 
    注释掉bind-address           = 127.0.0.1
    sudo service mysql restart