1.登录mysql :   mysql -u root -p

2.输入密码：    Enter password:  xxxxx

       ------ Server version: 8.0.15 MySQL Community Server - GPL

3.进入mysql数据库：use mysql;

4.设置允许远程用户访问：   

MySQL [mysql]> GRANT ALL ON *.* TO ‘root‘@‘%‘

出现问题：ERROR 1410 (42000): You are not allowed to create a user with GRANT

原因：当前user表中没有root - %记录； 可以更新root - localhost 为 root - %

MySQL [mysql]> update user set host = ‘%‘ where user = ‘root‘;
出现问题：ERROR 1062 (23000): Duplicate entry ‘%-root‘ for key ‘PRIMARY‘

原因显示：host+user 应该是联合主键，冲突了

5.解决方法：

MySQL [mysql]> update user set host = ‘%‘ where user = ‘root‘ and host=‘localhost‘;

6.再次给用户root授权

MySQL [mysql]> GRANT ALL ON *.* TO ‘root‘@‘%‘ 

MySQL [mysql]> flush privileges;    

此时用navicat连接还是报错：Client does not support authentication protocol requested by server; 

原因是mysql8默认的加密方式为caching_sha2_password 与mysql5的加密方式mysql_native_password 不同

7.解决方法-更新用户加密方式：

MySQL [mysql]> ALTER USER ‘root‘@‘%‘ IDENTIFIED WITH mysql_native_password BY ‘密码‘;

查询一下修改结果：MySQL [mysql]> select host,user,plugin from user;

其它：如果需要支持 root - localhost可以使用插入语句

 MySQL [mysql]> insert user (user, host, ssl_cipher, x509_issuer, x509_subject) values(‘root‘, ‘localhost‘, ‘‘, ‘‘, ‘‘);

再查看：（注意 ssl_cipher, x509_issuer, x509_subject这几个字段没有默认值，不设置会提示错误）

mysql 8 设置允许远程连接 You are not allowed to create a user with GRANT