Solution to the Mysql ERROR 1045 (28000): Access denied for user root@localhost problem in Ubuntu system

First way:

skip-grant-tables: Very useful mysql startup parameters

Introducing a very useful MySQL startup parameter --skip-grant-tables. As the name implies, it is starting
mysql does not start grant-tables, authorization tables. What's the use? Of course it is useful after you forget the administrator password.

Start mysql with command line parameters: # /usr/bin/mysqld_safe --skip-grant-tables &

3. Change the administrator password:

use mysql;

update user set password=password('yournewpasswordhere') where user='root'; flush privileges; exit;

4. Kill mysql and restart mysql.

Then you can log in directly

Method 2:

View the path where MySQL is installed

Then we change the root user's password,

Check the default password first

Then log in directly

Then change the default root username and password

GRANT ALL PRIVILEGES on *.* to 'root'@'localhost' identified by 'password';
flush privileges;

mysql>update mysql.user set password=password('new password') where User="test" and Host="localhost";

mysql>flush privileges;

mysql>delete from user where User='root' and Host='localhost';

mysql>flush privileges;

mysql>grant select,delete,update,create,drop on *.* to test@"%" identified by "1234";

mysql> UPDATE user SET Host='127.0.0.1' WHERE User='root' AND Host='localhost';

mysql> flush privileges;

Change Grant_priv to 'Y' (flush privileges; (execute this statement or restart MySQL to take effect)), update mysql.user set Grant_priv='Y' where user='ptmind';