MySQL-1698 : Access denied for user 'root'@'localhost'解决方法

用root用户连接MySQL 数据库报"ERROR 1698 : Access denied for user ‘root’@‘localhost’" 错误。
**客户端：**terminal，Navicat，连接都该错误报错误.
**系统环境：**ubuntu 18,MySQL5.7
**原因：**The reason is that recent Ubuntu installation (maybe others also), mysql is using by default the UNIX auth_socket plugin.

Basically means that: db_users using it, will be “auth” by the system user credentias. You can see if your root user is set up like this by doing the following:

$ sudo mysql -u root # I had to use “sudo” since is new installation
mysql> USE mysql;
mysql> SELECT User, Host, plugin FROM mysql.user;
±-----------------±----------------------+
| User | plugin |
±-----------------±----------------------+
| root | auth_socket |
| mysql.sys | mysql_native_password |
| debian-sys-maint | mysql_native_password
±-----------------±----------------------+

As you can see in the query, the root user is using the auth_socket plugin
There are 2 ways to solve this:
You can set the root user to use the mysql_native_password plugin
You can create a new db_user with you system_user (recommended)
Option 1:

$ sudo mysql -u root # I had to use “sudo” since is new installation
mysql> USE mysql;
mysql> UPDATE user SET plugin=‘mysql_native_password’ WHERE User=‘root’;
mysql> FLUSH PRIVILEGES;
mysql> exit;
$ service mysql restart

Option 2: (replace YOUR_SYSTEM_USER with the username you have)

$ sudo mysql -u root # I had to use “sudo” since is new installation
mysql> USE mysql;
mysql> CREATE USER ‘YOUR_SYSTEM_USER’@‘localhost’ IDENTIFIED BY ‘’;
mysql> GRANT ALL PRIVILEGES ON . TO ‘YOUR_SYSTEM_USER’@‘localhost’;
mysql> UPDATE user SET plugin=‘auth_socket’ WHERE User=‘YOUR_SYSTEM_USER’;
mysql> FLUSH PRIVILEGES;
mysql> exit;
$ service mysql restart

Remember that if you use option #2 you’ll have to connect to mysql as your system username (mysql -u YOUR_SYSTEM_USER)

Note: On some systems (e.g., Debian stretch) ‘auth_socket’ plugin is called ‘unix_socket’, so the corresponding SQL command should be: UPDATE user SET plugin=‘unix_socket’ WHERE User=‘YOUR_SYSTEM_USER’;