mysql> use mysql
ERROR 1044 (42000): Access denied for user ”@’localhost’ to database ‘mysql’

Solution:

# mysqld_safe –skip-grant-table
161104 10:36:00 mysqld_safe Logging to ‘/var/log/mysqld.log’.
161104 10:36:00 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

At this point the terminal is in a waiting state, open another terminal to change the root password of mysql

# mysql -u root

mysql> update user set password=PASSWORD(”) where user=’root’; # Here I set the root password to null
Query OK, 0 rows affected (0.00 sec)
Rows matched: 3 Changed: 0 Warnings: 0

mysql> delete from user where user=”; # Delete this ”@’localhost” user, otherwise it will still default to this user after login

Query OK, 2 rows affected (0.00 sec)

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

mysql> quit

After changing the root password of mysql, stop the mysqld service, at this point, the above terminal will stop waiting.

# /etc/init.d/mysqld restop
Stopping mysqld: [ OK ]

Starting mysqld: [ OK ]

The problem is solved by logging into mysql again.