运行时mysql访问被拒绝

Question

mohammadhb@mohammadhb-P43-ES3G:~$ sudo -i
[sudo] password for mohammadhb: 
root@mohammadhb-P43-ES3G:~# mysql
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
root@mohammadhb-P43-ES3G:~# clear
root@mohammadhb-P43-ES3G:~# mysql
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)