第一种方法：

/local/server/mysql/bin/mysqladmin -u root password ‘new_password’
由于mysql安装的时候，默认没有root密码，安装时可用此方法设置root的密码。

[root@uc ~]# /local/server/mysql/bin/mysqladmin -u root password 'zhcw123'
/local/server/mysql/bin/mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: NO)'
[root@uc ~]#
第二种方法：

登录mysql数据库/local/server/mysql/bin/mysql -u root -pzhcw123

[root@uc ~]# /local/server/mysql/bin/mysql -u root -pzhcw123
Welcome to the MySQL monitor.? Commands end with ; or \g.
Your MySQL connection id is 61
Server version: 5.0.90zhcw-log Source

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use mysql
Database changed
mysql>
mysql>UPDATE user SET password=PASSWORD(’new_password’) WHERE user=’root’;

mysql>FLUSH PRIVILEGES;

第三种方法：

mysql>SET PASSWORD FOR root=PASSWORD(’new_password’);