1. 未设置密码前：

ysql> select host,user,password from user;
+-----------+------+----------+
| host      | user | password |
+-----------+------+----------+
| localhost | root |          |
| xin.mysql | root |          |
| 127.0.0.1 | root |          |
| localhost |      |          |
| xin.mysql |      |          |
+-----------+------+----------+
注释：第一次设置密码和更改密码命令不一样。

2. 设置密码命令：

#/usr/bin/mysqladmin -u root password 'new-password'
#/usr/bin/mysqladmin -u root -h xin.mysql password 'new-password'

3.设置密码后；

[root@xin ~]# /usr/bin/mysqladmin -uroot password '12345qwert'
[root@xin ~]# /usr/bin/mysqladmin -uroot -h xin.mysql password '12345qwert'
mysql> select host,user,password from user;
+-----------+------+-------------------------------------------+
| host      | user | password                                  |
+-----------+------+-------------------------------------------+
| localhost | root | *41DA2FB717B0761640FBDD9C889C372DC8CB6FAA |
| xin.mysql | root | *41DA2FB717B0761640FBDD9C889C372DC8CB6FAA |
| 127.0.0.1 | root |                                           |
| localhost |      |                                           |
| xin.mysql |      |                                           |
+-----------+------+-------------------------------------------+
4.登录mysql数据库
[root@xin ~]# mysql
ERROR 1045 (28000): Access denied for user (using password: NO)  //设置密码后，还用mysql命令直接登录报错。

[root@xin ~]# mysql -uroot -p12345qwert  //root本地登录

mysql> select user();
+----------------+
| user()         |
+----------------+
| |
+----------------+

[root@xin ~]# mysql -uroot -p12345qwert  -h xin.mysql //远程主机登录 -h

mysql> select user();
+----------------+
| user()         |
+----------------+
| |
+----------------+