ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

chanyenping@chanyenping:~$ mysql ERROR 1045 (28000): Access denied for user 'chanyenping'@'localhost' (using password: NO) chanyenping@chanyenping:~$ mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 5 Server version: 5.0.75-0ubuntu10 (Ubuntu) Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql>