先停止mysql服务

macos 可以用

brew services stop mysql

或

mysql.server stop

用mysqld_safe启动mysql

mysqld_safe --skip-grant-tables

mysql 5.7或以上可以在 my.cnf配置文件 [mysqld] 添加

[mysqld]
skip-grant-tables

进入mysql命令行

设置root密码

set password for 'root'@'localhost' = password('你的密码');

报错

ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement

解决：命令行先输入，再输更新密码命令

FLUSH PRIVILEGES;

用update user表方式更改：

use mysql;

update user set password=password('your_password') where user='root' and host='localhost';

flush privileges;

如果报错，可以试试

update user set authentication_string=password('你的密码') where user='root';
update user set plugin="mysql_native_password" where user='root';

刷新

flush privileges;

退出

quit;

启动mysql

brew services start mysql

或

mysql.server start

完成!