方法1： 用SET PASSWORD命令

mysql -u root
mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWord('newpass');

方法2：用mysqladmin
mysqladmin -u root password "newpass"
如果root已經設置過密碼，采用如下方法
mysqladmin -u root password oldpass "newpass"

方法3： 用UPDATE直接編輯user表
mysql -u root 
mysql> use mysql;
mysql> update user SET Password = PASSWord('newpass') where user = 'root';
mysql> FLUSH PRIVILEGES;


在丟失root密碼的時候，可以這樣:

mysqld_safe --skip-grant-tables&
mysql -u root mysql
mysql> update user SET password=PASSWord("new password") where user='root';

mysql> FLUSH PRIVILEGES;